Will attempt to slowly compile dex differences in this post. Starting with silver because more of the gold ones may be identical. Given that some pokemon are still very different in this stage, though, this may not be true.
Unless noted otherwise, the name is the same as in the final version of GS.
Take translations with a grain of salt since I'm nonnative.
Silver
Chikorita: Its nice-smelling leaf has the ability to probe its surroundings.
Bayleef: Smelling the pleasant, spice-like aroma that emanates from around its neck causes one to feel hungry.
Quagsire: same
Sunkern: Asserted as fact rather than "it is said"
Sunflora: When the sun goes down, it closes its petals and stands still. Without light, it is not active.
Sentret: same
Lanturn: same (wrong name here)
Aipom: Lives high up in trees. When it jumps from branch to branch, it deftly uses its tail to keep its balance.
Wooper: When on land, a poison-infused mucous membrane is excreted. (wrong name here)
Espeon: By utilizing its 4 ears, even with its eyes closed, it knows all that occurs around it. // this is fuckin badass and the final version is hella watered down
Umbreon: same
Furret: It digs through the ground and makes a tight nest that only it can enter. It goes in tail-first.
Murkrow: same
Slowking: same
Misdreavus: When it feels as if the hair on the back of your head is being pulled, a Norowara has appeared behind you. // Still named Norowara, which apparently turned into Misdreavus, since this is very similar to the Silver Dex entry. Neat.
Unown: same
Wobbuffet: It hides away in dark places. It doesn't make attacks on its own, but when counterattacking, it returns damage threefold. // Still called Twinz. "Shadow Pokemon". Wow, Wobbuffet (body and tail) started out from a Girafarig prevo?
Girafarig: same
Pineco: same
Shuckle: At some point, it works its way into a pot. What its true body is like is unknown. // lmao"potpot" is literally a pokemon in a pot. Did not notice til a week later, but its species name is literally the "Earthenware Pokemon", specifically the fired kind. Very silly.
Dunsparce: It is very persistent. Once it decides on a target, it follows it to the ends of the earth. // fuckin badass
Steelix: Compressed by the weight of the ground, it has come to possesses a hardness that far surpasses that of diamond. // similar to gold final
Gligar: same
Snubbull: same
Granbull: If it senses a smell that it has not smelled before, it lets out a low roar.
Qwilfish: In an instant, it can swallow 10 liters of water to expand its stomach and appear larger. // "Pukuu"
Scizor: Due to its fondness for shores, it is thought to be a species close to those like Krabby. // ??? lol
Forretress: It eats all kinds of tree bark. It sticks the leftovers onto its shell and makes its shell sturdy. (wrong name here) // also "bagworm pokemon" like pineco above
Heracross: same
Sneasel: same // here "weasel pokemon"
Teddiursa: It's skilled at climbing trees. It picks berries in high places and eats them before they fall down.
Ursaring: It is unsurpassed in its ability to discern smells and is always walking around while having its nose stuck out.
Magcargo: It has a lava-like body, but, for some reason, when it basks in the sun, its skin hardens.
Corsola: In order to protect the carefully-raised tip of its head from being eaten by Staryu, it lives in groups.
Swinub: same
Piloswine: Both of its eyes are covered in fur, but, relying on sound, it acquires its target and rams towards it in a beeline. // "pig boar pokemon" like swinub
Slugma: same
Remoraid: same, but it mentions Mantine by current name of Hane'ei // both are "Jet Pokemon"; final game has "funsha (Jet, but in Japanese and not a transliteration) Pokemon"
Octillery: very close, but "crawls into" rather than "steals"
Hoothoot: same
Delibird: same
Mantine: uses slightly different word for ocean (おおうなばら vs. final ひろい うみ) but otherwise same // "Hane'ei"
Skarmory: Because its nest is located in a high-up area where violent wind rages, its skin has steadily become harder. // "Yoroidori"
Houndour: Pokemon that hear its ominous cry shake and return to their nests as fast as they can. // used for Houndoom in final
Houndoom: Parts of its skin are hardened and almost appear as if its bones have been flipped out.
Noctowl: same
Kingdra: Because it surrounds its body with ink it emits from the water in order to conceal itself, its appearance is hard to determine.
Phanpy: It can move its long upper jaw more freely than its limbs and it uses it to ward off enemies. // "Paon"; why this is called an upper jaw and not a trunk is absolutely beyond me
Donphan: same
Meganium: same
Porygon: same as final gold
Stantler: same
Smeargle: same
Tyrogue: same // "Gong"
HItmontop: same // it has eyes now instead of the horrifying pseudo-claydol in SW97
Smoochum: // Named Kisskiss! Differs from both SW97 and final!
Elekid: On days with poor weather, blueish-white electrical current flows in the gap between its horns.
Magby: same
Miltank: same
Blissey: same
Raikou: same // "Rai"
Entei: same // "En"
Suicune: very slightly different wording (みせる vs. final あらわした) but otherwise same // "Sui"; "Milky Way Pokemon"
Larvitar: Its soft body can absorb the shock from any attack and then relax. // It's actually supposed to look like a fucking mischevous blob lmao
Pupitar: Although it is in a pupal state, it can move unrestricted. It comes charging with its hard shell. // "charge" may literally be the move "Take Down"
Tyranitar: Its forehead is said to be the hardest thing on land. Charging with its forehead, there is nothing it cannot break. // Did you know? Tyranitar = Rampardos. same point on "charge" as above
Lugia: same
Ho-oh: same
Celebi: Nobody knows details about its rumored existence. Currently under thorough investigation. // "Plant Pokemon". Seems time travelling was not its gimmick yet.
Ledyba: same
Ledian: specifically mentions that it has 7 stars and is called "7 Star Pokemon". seems it went through a lot of different star numbers - 3 in SW, 7 here, 5 in final, go figure. Ledian == Marshadow?????
Spinarak: If suddenly attacked, it raises its back and shows the face pattern on it; while the enemy is surprised, it flees.
Ariados: It starts to eat after emitting a thread from its mouth and its rear and restraining its prey. // Named "Ariadne", which is different form both SW97 / final
Cyndaquil: same
Crobat: same
Quilava: The fur that covers its body does not burn in any fire. It is fine even in lava. // very similar
Yanma: same
Chinchou: same
Pichu: same
Cleffa: same
Typhlosion: same
Igglybuff: same
Togepi: same
Togetic: Flying floatily, it looks for a kind person that seems like they will grant it happiness.
Natu: same
Xatu: same
Totodile: Thrashes about more than one would imagine from its size. Teeth it loses from biting grow in one after the other. // same first sentence as final, same second sentence as first sentence of final Croconaw
Mareep: same
Croconaw: It spends most of its day with just its eyes and snout above the water's surface.
Flaafy: same
Ampharos: slightly different; "The bright light on its tail can be seen far away. It has been treasured since ancient times in place of a beacon."
Bellossom: same
Marill: same
Azumarill: same as final gold version
Feraligatr: same // "It is hard for it to support its own weight out of water, so it gets down on all fours. But it moves fast. " then why the fuck is it standing on two legs in every appearance???
Sudowoodo: same
Politoed: same
Hoppip: same
Skiploom: same
Jumpluff: same
before I sleep I don't want to do the whole of gold so I'll just do the ones I think are different
Gold
Espeon: It has developed extrasensory power. It appears that, using its whole body, it can even sense things one would not otherwise know.
Misdreavus: slightly different; final version mentions it is specifically a prank / trick whereas original does not
Unown: same
Wobbuffet: When it takes in the sun, it slowly splits, so it hides in dark caves.
Shuckle: Berries stored in its pot-like shell seem to eventually turn into alcohol. // so this is why they banned berry juice in lc
Dunsparce: When attacking prey, it hits it with its head, violently and very hard, in order to knock it unconscious. // how it feels to get paraflinched to death in gamefreak lore
Qwilfish: In order to make its body look bigger, it quickly swallows a lot of water to expand its stomach.
Scizor: same
Forretress: It has layered tree bark and made a sturdy shell, but the shell is heavy and it practically cannot move.
Sneasel: Its long, crescent-shaped claws are usually hidden in its fingers.
Larvitar: same
Pupitar: same
Tyranitar: same
Celebi: same as above
Ledian: same
Ariados: same
Feraligatr: slightly different; final adds "into shreds"
