If you are looking for the most basic differences, they would be overall size, magazine type, and caliber.
P220: 112mm barrel, single-column magazine, (.45 ACP) (10mm Auto)
P224: 89mm barrel, double-column magazine, (9x19mm Para) (.40 S&W) (.357 SIG)
P225: 99mm barrel, single-column magazine, (9x19mm Para)
P226: 112mm barrel, double-column magazine, (9x19mm Para) (.40 S&W) (.357 SIG)
P227: 112mm barrel, double-column magazine, (.45 ACP)
P228: 99mm barrel, double-column magazine, (9x19mm Para)
P229: 99mm barrel, double-column magazine, (9x19mm Para) (.40 S&W) (.357 SIG)
P239: 91mm barrel, single-column magazine, (9x19mm Para) (.40 S&W) (.357 SIG)
P245: 99mm barrel, single-column magazine, (.45 ACP)
As you can imagine, the 112mm barrel models are considered full-size, the 99mm barrel models are considered compact, and the 89mm/91mm barrel models are considered subcompact. They are all metal-framed and hammer-fired. They are usually DA/SA, though there are other trigger variants available (DAO, SAO, DAK). You asked specifically for P22x. The P239 and P245 also fall under the category you are referring to, despite their names. The calibers listed above are not absolute, but certainly the most common (especially in the USA). Differences more nuanced than these basically require going down the rabbit hole. Good luck