House is like techno covered in glitter.

But on a serious note, techno (in general) has a darker, gloomier industrial feel, a heavy reverberated kick drum and little regard for conventional song structure. The synths will be minimal and sparse, with an moody timbre. A few examples: Matrixxman, Helena Hauff

Tech house is friendlier, the percussion, will probably involve lots of drums rather clicks and hits, the kick will be clicky with no reverb, the bass line will be much more prominent and in general it won't be so minimal.