What is Satellite XM Radio? & what is the difference from real radio?

I wanted to know that, ALSO... I WANTED TO KNOW IF YOU COULD LISTEN TO YOUR FAVORITE RADIO STATION WHILE TRAVELING THOUGHT THE COUNTRY? For example, I live in Philly. My favorite radio station is Philly B101. So am I able to listen to that station on XM Satellite Radio while I travel through the country state from state?