I sometimes hear the wrong one spoken.

Problem:
“Different” and “differently” are not synonyms.

Explanation:
“Different” is an adjective. “Differently” is an adverb.

Solution:
Use “He looks different.” when you want to say that someone’s appearance has changed.
Use “He looks differently.” when you want to say that someone’s perspective has changed or that someone’s perspective is different than someone else’s perspective.