These are two great handguns manufactured by the premier company Heckler & Koch. In 1995, they developed the HK USP Compact, the with a few modifications they brought the 45C to market in 2007.
Range Report: HK45 Tactical - The Shooter's Log
Handgun Capacity: Quality or Quantity? - The Shooter's Log
Lori L. Lake: Part 2 - Guns, Guns, Guns: Outfitting Your Sleuth(s) - Lee Lofland
The Heckler & Koch USP and the Evolution of the H&K .45 Auto Caliber Handguns – Small Arms Defense Journal
Why are 1911s and HK USP pistols so popular? - Quora
HK45 Compact vs USP45 Compact, I can't decide
Heckler & Koch - Which .45 do you prefer? HK45 Vs. HK45 Tactical
an actual gun thread in GD!!! HK USP .45 range report
HK USP 45 field pistol [Archive] - Page 4
Comparing the HK45 to the FNP 45
Hk USP compact 45 vs Hk45c
Dick Jones, Author at Gun Digest