"I like exercise."
Translation:저는 운동을 좋아합니다.
It's the level of politeness. The first one is just polite and the second one is formal polite (a higher level of politeness).
It means the same thing, but with different moods (formal, informal, etc.) It's best to familiarize yourself with the different forms of the same word since they change depending on the situation (who you're talking to, etc.)
From my experience, the former is used more commonly. The latter is super formal and you would use it in situations like interviews
One is polite and the last one is formal. Longer the ending means the more formal.