The thing about angels

As a child, I was always told that the only real fundamental difference between angels and human was that angels didn't have a choice, they had to serve God, while we had the choice of whether or not we serve Him. Now that I think about it though, I don't quite buy it. Lucifer chose to rebel against God and the angels who followed him chose the same thing. Later, some angels chose to go onto Earth and have sex with women. That, supposedly, is how giants were made. It seems to me like angels have a lot of choice. Besides that we have to be on Earth before we can go to Heaven, what is the difference?