The big changes in the mod pack include:
origins: players pick their character's origin and by doing so acquire new abilities and weaknesses
YUNGS mods, better nether, Towns and Towers, and OTBYG: changes vanilla structures to be vaster and adds detail along with changes terrain generation to add more biomes and alter the vanilla ones.
twilight forest: adds a new magical feeling dimension to the game with progression, bosses, and dungeons to explore.
BLAST: Adds new explosives to the game like portable bombs and Mining TNT to make TNT more useful.
Enhancements: A massive overhaul to enchanting, removes most vanilla enhancements and adds more unique ones, you can only pick one so choose wisely.
there are a few more small changes & quality of life improvements in the mod pack like minimaps and armor upgrade paths. Why not give it a try?

