That is a demonstrative adjective so of course, one of its uses is to demonstrate noun and signal. ¨That(He) is the man in the blue shirt¨ Of course it is also used to add relative or additional information to a clause or phrase. For examle, ¨He is the man that is wearing the blue shirt¨ or He is the man that is wearing the shirt, which is blue. You will find that which is used mostly with things and that-who-or whom is used with people. I hope that this helps. Let me know if you have more questions.

almost no difference except which is used for non human, things, and that used with human and non-human example, this is the man that i met yesterday that is the man whom i met yesterday both sentences are correct but i can not say that is the man which i saw yesterday, it is wrong because which is can not be used with human hope that helps

tomo, thanx for the question. was also interested.