Basically, proper track frames have steeper angles than normal and short back ends, for quicker handling (beware riding track bikes on the road, they're a bit scary sometimes). They have higher BBs to avoid pedal strike (so most people got for 1 or 2 sizes smaller than their normal road bike). This is a basic description of proper track geometry.

Some have forward-sloping TTs to get the bars down lower for better aero. The idea is taken to the limit with 650 front wheels, to get the front uber-low - see Moser's Hour bike; aka Funny Bike (this is what I consider to be pursuit style, but I may be wrong).

'Street geometry' is simply a bike with normal road geometry (whatever that is ) on a frame that looks like a track frame; it may just have track ends, it may have 120mm rear spacing, it may have no bottle braze-ons, but most will have a rear brake hole (but may not have any cable guides). A good example of this is the Surly Steamroller.

Hope this helped.