"Welcome! Nice to meet you!"
Translation:환영합니다! 만나서 반갑습니다!
-하다 is 'to do' and -입니다 is 'to be'. One describes an action, the other a state.
English has many greetings as well. Hey, hello, how you doing? And many more.
안녕하세요 means hello, not welcome. It may be in the same spirit, but it's not quite the same.