I wouldn't call Jazz melodies 'conformist' in the political in any way. In fact, the birth of the jazz age was heralded with as much "what's wrong with these kids today" sort of attitude as the birth of Rock and Roll.
Now, from a theory standpoint, the two are sometimes difficult to seperate as they are not mutually exclusive. Both are commonly played in swing time, both make extensive use of polytonality, and both often share forms.
Early jazz is based on vi ii V I progressions but usually with a lot of secondary dominants making it more like V/ii V/V V I. Early blues does this also, but more commonly as part of a 12-bar form.
While we are on the subject, 12 bar form is the staple for blues, but NOT the only form by far! In fact, early blues was a lot more open than modern blues and you would see 12-bar 8-bar, 16-bar, formless progressions, and many other ideas. Some regidly with domintant 7th chords throughout, some with substitutions and secondary dominants.
Also interesting to note that the 12 bar form is common in jazz as well. One of the major differeneces is that even though they are both played in swing time (similar to 12/8 as an expression of unequal 8ths in 4/4) blues falls more on the down beat and jazz not so much.
Melodically, jazz improvisation tries to steer away from the tonic and even away from triad chord tones where blues tends to use the tonic and 'blue' notes.
There are so many details that it is difficult to express them all.
The really short answer is that blues comes from the heart and jazz from the head.
· 1 decade ago