This is a brilliant album (a compilation of the Scottish post-rockers BBC Sessions) that I have been listening to again and again. I've never seen Mogwai live so I've had to rely on the BBC to hear anything outside their album sound. There's not a huge difference between the studio recordings and some of the stuff here except that of course familiarity and practice tends to make the songs sound slicker.
Perhaps the major difference is that almost every track here sounds more powerful than the studio albums. Regardless, it's a superb introduction to Mogwai if you aren't already a fan and a great retrospective if you are.