i can't really explain it.
if you've come up through the harder and loopier forms of techno, you're really gonna have a job getting your head around it, but to me Detroit techno means that original ethos of techno that first made the genre back in the 80's.
best way to start to understand it, i think, is to try to get hold of 'the detroit sound of techno' comp or some of the earlier techno comps. quite a few of the early 'jack trax' comps had some nice detroit sounding bits on.
ok so back to what the music is all about. well it's that feeling of futurism, that feeling of metropolis, star trek, sci-fi, i dunno. a typical thing that makes detroit sounding techno so good are those mechanical sounding hi-hats and dark, scary futuristic bass. strings have featured in alot of detorit tracks and they make then sound beautiful, but still incredibly futuristic.
you know, if you can't figure it out, lock yourself in a dark room in a basement and tell yourself the aliens are outside. then play model 500 'no ufo's'.
good luck anyway, music is so incredibly personal and there's no wrong or right way to listen, but i'm sure lots of ppl can pipe up here and help you out.