What's the difference?

I just need to know something. I have a friend that has DSL and she 
claims that it is broadband. She gets her service through the telephone 
company. She also claims her DSL is faster than what I have. I have Road 
Runner through the cable company. C'mon seriously, which is faster and 
what is the difference between DSL through the phone company and 
broadband through cable? Actually, I didn't know DSL WAS broadband! Can 
anyone clear this up for me?