Nervous just suggests that you’re not quite settled or a little worried largely due to unfamiliarity. Apprehensive is more like fear and panic, that something bad might happen. You probably will be nervous while doing an exam, but seldom apprehensive. Whereas you might be apprehensive to go out at night because there is a lot of crime in the area. Hope this makes sense, message if you have any other questions :)

Hi Diego, Nervous could refer to anything you are worried about. E.g. I feel very nervous because I have a test tomorrow. Or I am nervous that I left the cake in the oven for too long. Apprehensive is a /deep/ fear of something (specific) that may happen. e.g. Since the plane crash in 2004, he felt apprehensive about flying ever since. Hope this helps!