Tech is basically when someone does "combo" tricks. Tech would be like (example: ) 180 bar to fakie, to fakie 3, to barspin, to downside out. Same would apply with using manuals and everything else to do a "string" of tricks. Tech is like a bunch of little tricks thrown together and balance is usually key. Consistency is big too because more than one trick is done. Whipping a 9 stair would be the opposite of tech.
For Tech please refer to (Jordan Jasa)