The difficulty levels in SE were all shifted down by one, except for Dante Must Die mode, which is the same as the original.
Depends on what part you mean, if you mean DMC3 then the SE version had two modes "Gold" and "Yellow".
Yellow being the original version of the game while Gold is the newly added one.
"Easy difficulty" was also thrown in the mix.
Difference between the two modes was that Yellow had limited continues while Gold had infinite continues.(In Yellow mode, if you lost all your continues you had the restart all over again from the beginning.)
The SE version also had rebalanced difficulty, if this is really a big impact I don't know since I only have the SE version.
what would I miss if I would go for the original one?
These are the extras that you only have in DMC3 SE
- Gold mode
- Easy difficulty (Don't know if this was also present in normal DMC3)
- Play as Vergil
- New boss fight added
- Survival mode
- Turbo mode (20% faster game speed)
If you have any more questions, then please don't be afraid to ask.