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.
Heckler & Koch USP 45 vs Heckler & Koch HK45 size comparison
Hk USP compact 45 vs Hk45c
Heckler & Koch UMP - Wikipedia
an actual gun thread in GD!!! HK USP .45 range report
FNP-45 Tactical vs HK 45 - which would you pick? [Archive] - Forums
Battle of H&K .45s: HK USP Compact vs HK 45C
10 Best .45 ACP Pistols (That Aren't 1911s) - Pew Pew Tactical
From the Safe: HK 45 Compact
Why are 1911s and HK USP pistols so popular? - Quora
The Heckler & Koch USP and the Evolution of the H&K .45 Auto Caliber Handguns – Small Arms Defense Journal
A Battle of HK .45s: HK USP Compact vs HK 45C
9mm vs .45 ACP [Debate Finally Settled] - Pew Pew Tactical
Hk USP compact 45 vs Hk45c