Player Characters: 6
Transformations: 1
Items: 130 (35 active, 95 passive)
Trinkets: not present
Pickups: 9 (3 hearts, 1 key, 2 coins, 3 bombs)
Pills: 17
Consumables: 21 ( 21 cards)
Interactables: 2 (2 chests)
Enemies: 50
Bosses: 26
Minibosses: 7
Chapters: 5
Challenges: not present
Endings: 12 (Including Epilogue)
Rooms: ?
Achievements: 52
Songs: 30

This is including the free updates to the base game such as the major Halloween update, but does NOT include Wrath of the Lamb or the Eternal Edition update.

Player Characters: 1
Transformations: 0
Items: 66 (17 active, 49 passive)
Trinkets: 34
Pickups: 4 (1 heart, 1 key, 1 coin, 1 bomb)
Pills: 3 new colours, 4 new effects
Consumables: 5 (5 cards)
Interactables: 1 (1 chests)
Enemies: 27
Bosses: 17
Minibosses: 8
Chapters: 6
Challenges: 10
Endings: 2
Rooms: ?
Achievements: 47
Songs: 10

This includes the free Eternal Edition update.
New major feature: Trinkets
New major feature: Curses
New minor feature: Devil Beggar
New special rooms: Angel Room, Curse Room, Sacrifice Room, Boss Challenge Room, Library, Super Secret Room

Player Characters: 7
Transformations: 1
Items: 196 (52 active, 144 passive)
Trinkets: 34
Pickups: 13 (4 hearts, 2 keys, 3 coins, 4 bombs)
Pills: 21 effects
Consumables: 26 (26 cards)
Interactables: 3 (3 chests)
Enemies: 77
Bosses: 43
Minibosses: 15
Chapters: 11
Challenges: 10
Endings: 14 (Including Epilogue)
Rooms: ?
Achievements: 99
Songs: 40

This includes the free Eternal Edition update.

Player Characters: 11
Transformations: 2
Items: 341 (74 active, 267 passive)
Trinkets: 60
Pickups: 18 (6 hearts, 3 keys, 4 coins, 4 bombs, 1 battery)
Pills: 9 colours, 28 effects
Consumables: 40 (32 cards, 8 runes)
Interactables: 4 (4 chests)
Enemies: 196
Bosses: 60
Minibosses: 20
Chapters: 12
Challenges: 20
Endings: 17 (Including Epilogue)
Rooms: a lot idk
Achievements: 178
Songs: 32

New game mode: co-op but only with stupid babies 💀
New major features: seeds, upgradeable shops, multiple save slots, analog controller support, runes.

Player Characters: 2
Transformations: 9
Items: 95 (19 active, 76 passive)
Trinkets: 29
Pickups: 4 (1 heart, 2 coins, 1 bomb)
Pills: 4 colours, 11 effects
Consumables: 5 (2 cards, 1 rune, 2 miscellaneous)
Interactables: 3 (2 chests, 1 sack)
Enemies: 40
Bosses: 10
Chapters: 5
Challenges: 10
Endings: 1
Rooms: 1000+
Achievements: 98
Songs: 9

New game mode: Daily runs
New minor feature: Options to display picked up items on screen

Player Characters: 2
Transformations: 4
Items: 121 (30 active, 81 passive)
Trinkets: 38
Pickups: 5 (4 hearts, 1 key)
Pills: 8 effects
Consumables: 9 (8 cards, 1 rune)
Interactables: 1 (1 chest)
Enemies: 21
Bosses: 6 (including Ultra Greedier)
Chapters: 1
Challenges: 5
Endings: 2
Rooms: 1500+
Achievements: 127
Songs: 4

This includes all 5 booster packs.
New game mode: Greedier (Greed hard mode)
New major feature: Bestiary
New major feature: Victory Lap and Rerun
New minor feature: Found HUD (official implementation of Missing HUD mod)
New minor feature: Charge bars

Player Characters: 19
Transformations: 0
Items: 172 (47 active, 125 passive)
Trinkets: 61
Pickups: 10 (1 heart, 1 coin, 3 bombs, 2 poops, 3 batteries)
Pills: 1 colour, 4 effects, and new type of pill that has a more powerful effect for each pill
Consumables: 43 (24 cards, 1 rune, 18 miscellaneous)
Interactables: 6 (5 chests, 1 sack)
Enemies: 100+
Bosses: 33
Minibosses: 2
Chapters: 9 (including the Ascent)
Challenges: 10
Endings: 2
Rooms: 5000+
Achievements: 234
Songs: 27

Features almost the entire Antibirth mod with many updates and reworks as well as twice as much brand new content.
Includeds the updates to Repentance adding 3 extra passive items and 1 boss.
New major feature: Reworked co-op mod akin to True Co-op mod
New major feature: Red key active item
New major feature: New special rooms including Planetariums, Ultra Secret rooms, Red rooms
New minor features: Horse pills and golden trinkets

Player Characters: 34
Transformations: 15 (Including Super Bum)
Items: 719 (170 active, 549 passive)
Trinkets: 188
Pickups: 37 (12 hearts, 4 keys, 7 coins, 8 bombs, 2 poops, 4 batteries)
Pills: 14 colours, 51 effects
Consumables: 97 (66 cards, 11 runes, 20 miscellaneous)
Interactables: 14 (12 chests, 2 sacks)
Enemies: 322
Bosses: 103 (Including both Ultra Greed and Ultra Greedier)
Minibosses: 20
Chapters: 27 (Including The Ascent)
Challenges: 45
Endings: 23 (Including Epilogue)
Rooms: 22 000+
Achievements: 637
Songs: 94

Includes updates added to Repentance

Player Characters: 2
Transformations: 0
Items: 87 (27 active, 60 passive)
Trinkets: 18
Pickups: 2 (2 hearts)
Pills: 3 effects
Consumables: 4 (4 runes)
Interactables: 0
Enemies: 80
Bosses: 16
Chapters: 4
Challenges: 5
Endings: 1
Rooms: 4000+
Achievements: 43
Songs: 48

New major feature: True co-op with multiple characters

Player Characters: 1
Items: 14
Trinkets: 10
Pickups: 12 (2 hearts, 9 keys, 1 coin)
Consumables: 8 ( 1 cards, 7 miscellaneous)
Interactables: 3 ( 1 chest, 2 sacks)
Enemies: 250+
Bosses: 12
Mini bosses: 2
Chapters: Huge overhaul to all game floors including custom textures, rocks, pits, backdrops, grid entities, etc and brand new unique biomes in some chapters
Challenges: 3
Rooms: 15 000+
Achievements: ?
Songs: ?

New game modes: Easy Mode, Mern Mode
New obstacles

Player Characters: 5 (2 challenge exclusive, 1 tainted)
Items: 146 (40 active, 106 passive)
Trinkets: 231 (49 normal trinkets, 121 rocks, 33 fossils, 28 geodes)
Pickups: 26 (10 hearts, 8 keys, 5 coins, 1 bomb, 2 batteries)
Pills: 21 new colours and 9 new effects (both including cyanide)
Consumables: 90 (60 cards, 0 runes, 30 miscellaneous)
Interactables: 6 (3 chests, 3 sacks)
Enemies: 500+ (wow!)
Bosses: 26
Minibosses: 3
Chapters: New floor overhauls for Repentance floors including new biomes: Junk Depths, Peepee Dross, Alt Mausoleum, Morbus and Psionic Sheol
Challenges: 10
Endings: 0
Rooms: 48 000+ (wow!)
Achievements: ?
Songs: 77

New game mode: The joke modes: Mern, Easy and Stable modes.
Wiki: https://fiendfolio.wiki.gg/wiki/Fiend_Folio_Wiki