Is chron colitis like acute colitis?

Can be: Crohn's as well as other colitis entities can be both acute or chronic. Acute colitis is a general term that includes the above but also can include ulcerative colitis, antibiotic associated colitis, ischemic colitis to name a few.

Colitis includes : Inflammatory diseases, such as crohn's disease or ulcerative colitis, and other causes such as infections or ischemia. So "colitis" is a more general term, whereas "crohn's colitis" is a specific diagnosis.