A more more simple term- each Tamagotchi is different. From old 1996 ones, to huge eggs.
List of Tamagotchis - English
Vintage Era
P1
P2
Tamagotchi Angel
Garden Almost made to America.
Ocean
Connections
Tamagotchi Connection V1
Tamagotchi Connection V2
Tamagotchi Connection V3
Tamagotchi Connection V4
Tamagotchi Connection V4.5
Tamagotchi Connection V5
Tamagotchi Connection V5.5
Tamagotchi Connection V6 / Music Star
TamaTown Tama-Go
(Lol, I might be missing a few.
)
List of Tamagotchis - Japanese
P1 - Japanese Ver.
P2 - Japanese Ver.
Angelgotch - Japanese Ver.
Devilgotch
Umino - Japanese Ver.
Morino
Mothra
Tamagotchi Plus
Tamagotchi Plus 2
Chibi Tamagotch
Keitai Kaitsu Tamagotchi Plus
Keitai Kaitsu Tamagotchi Plus Akai
Chou Jinsei Enjoi Tamagotchi Plus
CYOI EnTama
Ura Jinsei Enjoy Tamagotchi Plus
Family Iro! Iro! Tamagotchi Plus
Royal Dream Family Tamagotchi Plus
Color Screens
Tamagotchi Plus Color
Tamagotchi Plus Color Hexagontchi Ver.
Tamagotchi Plus Color Exile Ver. (rare)
Tamagotchi iD
Tamagotchi iD Lovely Melody Ver.
Tamagotchi iD Detective Conan Ver. (rare)
Tamagotchi iD L
Tamagotchi iD L 15th Anniversary Ver.
Tamagotchi iD L Princess Spacy Ver.
Anime Linked
Lavutomo Keitai Himespe Phone
Tama Profy
Keitai Pashalin
Keitai Terulin
Melody Charm
Doremitchi
Sopratchi
Lol if I remember some more, I'll put more down.