Ecoder resolution terms

Hi,

I just need to know the difference between several encoder resolution terms.
I read the Gecko requirement and it mentioned a min. 200 line encoder
Searching to buy the encoders, I found the following resolution terms:
- Count per Revolution (CPR)
- Pulse per Revolution (PPR)

Could someone please explain the difference between the 3 terms.

Merry Xmas everybody.

Mina F.