They both mean "you". "Tu" is used when speaking informally such as with friends or children and it has to be when speaking with one person. "Vous" is always used when speaking to a group. It can be used when speaking to individuals but it is more formal. So you could use "vous" when speaking to someone you don't know or your boss, etc.
Tu = informal or singular Vous = formal or plural. Listen out for 'tutoyer' if speaking with a native speaker - theyre saying to refer to them using 'tu' instead of 'vous' although dont worry if you do get them mixed up - if they know youre not a native speaker then they'll understand.
so, i understand that "vous" and "tu" are for formal/informal, but is there a way to tell in these exercises which is which? in german, the verb changes depending on the number of people addressed, so if one uses a singular verb with a plural pronoun sometimes one can figure out who's talking. is there something similar in french?