It's like the diff. between electrical engineering vs electronics vs telecomunication ....
They all share some sort of stuff, but you will end up in diff. places ...
CS, SE and IT means what actually they mean ... with commons and diffs.
take the dictionary and look up for their meanings ... And thats what it is ...
Now, students who gradute CS might actually be interested is SE and IT graduates might be intereseted to work in CS domain ...
Take paper and write : what I what to do for the rest of [my] life?
Then ask teachers from CS,SE,IT what's best for you

Best regards