I have a Bongo 5HH right now as my main (well... only) bass. I've played a lot of SR5s at various music stores, but have never owned one (though I've come close).
There are a lot more differences than similarities regarding the two:
-First, the body wood. Bongos are made of basswood. I might be mistaken; but I don't think that musicman has used basswood in other designs.
-Also, the electronics are quite different. I'm no tech head, so I couldn't tell you any exact figures or anything.
-The bongos IIRC don't have a maple fretboard option.
-Another difference is the pickups. Looking at them, you'd think they're the same; but the Bongos have neomydium magnets in the p/u's.
-You have 24 frets (Bongo) vs. 22 (SR5).
-The Bongo also has a slightly wider neck (1/16 wider than the SR5).
-As well as the Bongo being a bit lighter (SR5s~10 lbs. / Bongos~9.4 lbs.)
As far as similarities, I think they both have the same bridge, and have maple necks with an 11" radius and 34" scale.
From a sound standpoint. I can sum up the sound of the bongo with two words: growl and bawls. The first time I went direct with the bass, I had the bass EQ cranked - causing the power amps to clip. The bass has thunderous low end unlike any other bass I've owned. Saying that, you'd think that there would be a lack of highs; but saying that would be completely facetious (spelling?).
Hope this helps in some way, shape, or form.