His actual songwriting is mostly in fusion with Earthworks and Bruford, although he contributed to other peoples' songs in Yes and King Crimson.
I've listened to all of Bruford's work, especially earthworks, it is fusion style, but he started with jazz and ended with jazz, his compositions however, I can't argue are not fusion, however they have more jazz elements than quite a bit of other fusion artists. He more resembles the chik corea style of fusion, which is the more jazz oriented area. However, his influences as people keep spouting are jazz oriented. Honestly I think it doesn't matter who developed from what. We're looking at their compositional ability, that is to write instrumental parts, either on sheet music or in their head, but it's the composing of the notes. The reason BW and Zappa are so far ahead is they've written parts for tons of different instruments, jazz, rock, and classically oriented, in the same songs, and how the parts compound upon eachother into sheer brilliance, which is what composition, and even symphonies, are all about. How hundreds of instrumentalists combine and compliment eachother musically into a masterpiece of art. I also feel influence is extremely important, but I also feel compositional ability is nearly equally important, and remember, especially in composition, skill is defined less by the technicality of the pieces and more by the musicality, making it extremely subjective. People could argue forever if Beehtoven, Bach, or Chopin/Liszt are the better composers. Chopin/Liszt are extremely technical, however, at least Liszt, sacrifices a lot of musicality and compositional versatility and complimentary parts for technical prowess, where Bach is arguably the most musical and gifted composer to ever touch classical music. However, Beehtoven is nearly on the level, if not on the level of musicality as Bach (had some of the most complex, brilliant, and beautiful chord resolutions and strange key changes that take a level of musicality and talent that rivals if not surpasses Beehtoven), but his massive influence and praise are what push him ahead to number 1 for probably eternity. Mozart gets ahead nearly purely on Influence and Acclaim, as his technicality and musical ability, though gigantic, don't compare to Beehtoven or Bach, or arguably Wagner.