Dear Lord, Radiohead are by far the superior band.
1) Thom York has far stronger and more versatile vocal range than Chris Thingummy. Have you ever heard Coldplay live? The vocals are embarrasingly weak.
2) Radiohead have far more diverse musical influences, from Miles Davis and Roland Kirk to Bowie, the Pixes, Autuchre . . the list goes on. Coldplay are basically Sigur Rós Lite with a dash of (THE ALSO FAR SUPERIOR) U2 and Kraftwerke.
3)Radiohead have much deper writing
Don't get me wrong, I don't hate Coldplay, and I think they have potential for the future (I liked their first album best) but they don't stand comparison with Radiohead.