Not exactly. There are two main patterns (DPMS LR-308 and Armalite AR-10) and a few variations of each. Everything from buffers and tubes, pivot and takedown pins, bolt catch, upper, lower, barrel nut, barrel, rails can vary between the two. Oh and bolts.
Most of the parts available are gonna be DPMS LR-308 (not gen 2) compatible, but different makers will have various specs for upper and lower and some makers will cross over between some DPMS and some Armalite pattern parts on their gun, some proprietary. I would say stick with DPMS pattern and try to get lower, upper, and LPK from same company. Make sure you get a short buffer if going with standard length buffer tube; I would recommended an extra power spring and heaviest buffer you can get. Most barrels will work. Rail wise will depend on the spec your upper is built to but most likely will be DPMS low I think - double check me on that. And make sure you get an adjustable gas block.
I started out with a kit and upgrading one piece at a time as I learn the platform. Very fun rifle platform to work with.