I agree that they have some stylistic elements that people are used to hearing as being totally opposed to one another (macho dude metal, whiny sensitive-dude banshee wailing) that creates the illusion that there is really a big difference in what they are doing.
I think Radiohead tends to go for more of a “retro” or “vintage” type of tone for it’s guitars and drums, while Tool tries for a more “modern” hard rock sound, but the other side of the coin is, they both are defining current rock production value in a similar way.
The guitar playing on a Radiohead album often reflects the influence of American bands like Fugazi or Sonic Youth, and similar sounding groups who are slightly more tonal (Pavement, Slint) who manage to keep their guitar parts very aggressive sounding while working outside of the power chord/pentatonic scale formulas that have became punk/metal/hardcore cliches in the ‘80s. I think Tool is obviously working from similar influences. For a band that is embraced by “metalheads” in America, it’s surprising that there is very little “chugga-chugga”, Metallica style palm-muted riffs, and realtively un-crunchy guitar tones. The guitars in these bands’ music sound very simlar to me.
I also hear Pink Floyd influences pretty strongly in both bands’ music.
I’m just saying I hear very simlar influences in these bands music, and to my ears, they sound as “similar” as any two bands do (like say, The Beatles and The Rolling Stones, who I think have some real obvious differences and simlarities, but are “contemporaries” and who worked in a very similar aesthetic realm). I think as time goes on, we’ll get a clearer picture of the similarities in the way they sound, especially since they are both very influential, and very much at the forefront of creative popular music. They are drawing from similar influences, and working with the same technology, and in a sense developing techniques for using new technolgy.
I think the big difference is that Radiohead tends to use some more complex, traditional harmony, while Tool keeps thing very primitive in that repsect. Tool also tends to focus more on repetition and tribal, percussion driven songwriting, but that’s not necessarily unfamiliar territory to Radiohead (“The National Anthem”). Still, those differences don’t sound very radical to me.
I also think they both suck. Joking… kind of… It all sounds pretty much like modern alternative rock to me. It sounds like stuff I’d hear on the radio. Probably the two best modern rock bands you might hear on mainstream radio.