Hmmm. Rather give examples in sentences. As it stands, it sounds out of place.

The first describes how sb perceives something. Or it could mean the behaviour is not typical of sb. It was strange for him = he perceived it as strange / he does not usually act in that way. The second can also describe sb's perception. Or it can describe how another person behaved to sb. They were a bit strange to him = he perceived them as strange / the acted strangely towards him.