Stations usually process the crap out of their music. They'll speed their songs up, compress them (creating loudness throughout the entire song), and selectively EQ certain frequencies (like bass or certain upper mids where vocals rest).
I think WNCI has sped songs up for years. It's usually most noticeable on slower tunes (ballads, singer/songwriter, or R&B). I'm pretty sure I've heard additional processing on The Blitz, Power 107, and WCOL too. CD101 doesn't seem to have any noticeable processing but sometimes I think they could use it.
Radio edits, on the other hand, are usually produced by the label in order to fit the format they're releasing the song to. For instance, they use to cut the rap parts in pop songs like TLC in order for non-rap pop stations to consider playing it. Those stations have kind of went by the wayside so you don't hear that as much. When alternative/rock songs crossover to pop, they usually cut solos and instrumentals in order for the song to fit a shorter "pop" length.
Average song intros these days is 7 seconds. Just enough time for a DJ to mention the artist, song name, and station you're listening to.