Music

One of the more blatant differences is the soundtrack. Danny Baranowky composed the original's soundtrack. Ridiculon composed Rebirth's soundtrack. While they both go for a creepy and disturbing tone, Danny's soundtrack is often more melodic and upbeat than Ridiculon's.

Oh, and just for fun, some Antibirth stuff will be here as well.

Basement

Boss

Caves

The Chest in Rebirth gets a brand new song. The original was not so lucky, as the song is just the regular boss theme.

Sounds

Enemies

wip

Bosses

Famine

Fly spawn

Charge

2nd phase attack