Why is he talking to other girls normally and when I talk to him he answers shortly and doesn't initiate?

there's a new guy i at work. when i first talked to him he was nice and asking questions and me also. i saw him last week and today and i noticed that he looks at me sometimes but not talking. i tried talking to him and he answers shortly, he doesn't initiate a talk with me but he talks to other girls which is weird to me. i noticed that his body language was toward me. the thing is that he is 4 years younger than me so i don't know if he is interested in me or not, it is confusing.

Why is he talking to other girls normally and when I talk to him he answers shortly and doesn't initiate?
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