I am not completely sure what you are asking for. I own a DPMS G2 Bull. The G2 is a small frame .308. That said, some of the parts are compatible with a regular AR15. Like trigger assemblies and SOME handguards. The .308 bolt carrier in a G2 is the same diameter as a AR15 but is about 5/8" longer. The bolt itself is proprietary to the G2 as well. The rifle is different enough that some of the common tools used will not work on a G2. For a simple bore guide for cleaning, I had to buy a .308 bore guide from JP Enterprises and have it turned down to the AR15 carrier diameter. Generation 1 stuff is much larger. A vise block for the G2 upper is different from an AR15 and a Gen1 rifle.
I have had my rifle for at least a couple of years. There may be more stuff available now than a few years ago. You will have to do your homework to find the stuff you need. My G2 is very accurate however. There are issues with magazines as well. Mine will not run Magpul magazines. I have to use the DPMS mags which are much more expensive.
I am not an expert on the platform, but letting you know what I have found in owning the rifle. Hope it helps.

 

Best I can put together after doing some reading at lunch is, the Gen II receivers are shorter than the Gen I and there's some weight savings by having the upper and lower shorter plus it looks like a full Gen II build might also be able to use AR15 handguards and such.

I was trying to find out the differences because some of the uppers I've seen listed for sale have a note about not being compatible with one generation or the other but many of the stripped lowers don't specify which generation they are.

Turns out Brownell's is blowing out the Gen I Aero Precision stripped lowers for $99 so I've got one ordered along with a Gen I compatible 16" upper.