u/cowboy_hmo

1st Photo: Army Custom G2 Combat Pants; usually these are the most popular model, these were used by both U.S. Army AWG and 10th Group CIF; these are uncommon nowadays but can pop out on eBay from time to time. Source: @TheFull9

2nd Photo: Army Custom G2 “Breacher Mod” Combat Pants; these are extremely rare since not many samples were made; these were used exclusively by Charlie Co. 1st Battalion (10th Group CIF) breachers although some of these were found in Fort Bragg area amongst SFARTAETC and other SF schoolhouses. Source: HopUp

3rd Photo: Army Custom G2 (Foliage Spandex) Combat Pants; extremely rare. These are pretty much the same as the tan spandex ones, most likely Crye saved money using the original tan spandex from Multicam ACs. Very few samples made, short use with some U.S Army AWG Troop members. Source: @TheFull9

4th Photo: Army Custom G2 (UCP Spandex) Combat Pants; extremely rare, likely precursors of the late Army Combat Pants, no much information on these. No exactly who may used them probably TRADOC. Source: @TheFull9

5th Photo: Experimental Combat Pants; main difference with these and the Army Custom ones is the cut of the pant, these are more similar to typical ACU pants, with interesting extras such as reinforced crotch (similar as Massif), also these pants have sand colored spandex in the upper butt area, buttons, loop buckles and tan knee velcro strips; likely use within USASOC/TRADOC. Source: u/verzuhility

6th Photo: Test Item Advanced Combat Pants; probably the most common ones, although these were made as test pieces they saw some use with U.S Army conventional units (especially 82nd Airborne and 101st Airborne), the pants itself came with G3 AirFlex knee pads in Foliage Green. Source: @TheFull9

7th Photo: Propper International Advanced Combat Pants; although these were OEM by Propper the main design was done by Crye Precision, these are a mix between the Army ACPs and Crye G3s; the main cut is similar as the Army ACPs (same pocket designs and waist taps), but with similarities with G3s such as the crotch spandex, knee pad adjustment and fabric knee covers. These use the same Foliage Green spandex like the older AC G2 variant. Not official use though but extremely rare. Source: SoldierSystems