Vita:Model Differences
Page content & researching collaboratively taken from io55.net's PS Vita page with permission.
There are four Vita models, of which only three are true portable game consoles.
Models
Models are arranged chronologically.
PCH-11xx "OLED" with Wi-Fi and 3G (2011-2013)
The fullest-featured version of the PS Vita. Easily identified by it's oval-shaped PS, start, and select buttons. It also features a heavier and thicker body than the Slim Vita, and features a metal trim surrounding the body, remenisant of the PSP. The PCH-11xx has a SIM card slot on the left side of the console. Featuring an OLED screen, a proprietary charger, and no built in memory card by default. The biggest reason one would prefer a PCH-10xx or 11xx over the PCH-20xx is for the OLED panel (and SIM slot with the 11xx). The OLED screen adds a color depth and screen quality not found on PCH-20xx, while the SIM card slot and 3G modem introduces a pretty useful mod not possible on the other models (plus GPS?). To be specific, it is possible to replace the 3G modem with an SD card reader, and optionally replace the SIM card slot with a MicroSD card slot with a relatively simple procedure. Such a mod allows the usage of a game cartridge and MicroSD card at the same time; other models need an SD2Vita which normally occupies the cartridge slot. However, there are some caveats to all of these benefits, as proprietary parts, “early OLED” problems, and generally clunkier ergonomics bring down the 10xx/11xx to being pretty evenly matched against it's successor.
PCH-10xx "OLED" with Wi-Fi (2011-2014)
Identical to the Wi-Fi and 3G version of the OLED Vita, except there is no 3G modem. This makes an internal MicroSD card mod impossible, or at least extremely difficult. See above for more detail about OLED Vitas.
PCH-20xx "Slim" (2013-2019)
A noteworthy update to the Vita, which improved battery life and ergonomics, changed out the propritary charging port to be standard MicroUSB, added 1GB of usable internal memory, reduced weight and thickness, yet removed the 1000's forward-thinking OLED panel. Easily identified by the PS, start, and select buttons being perfectly circular. This model also has a rounder appearance with no aluminum bezel on the edges and much less gloss on the housing. Both the PCH-20xx and PCH-10xx are quite evenly matched as devices, since the loss of the OLED in the 20xx was essentially “made up for” with the introduction of the previously mentioned general improvements found in the 2000.
VTE-10xx "PlayStation TV" or "PS Vita TV" (2013-2016)
Differing greatly from other Vita models, the PSTV is a consolized PS Vita. In Asian regions, the console was given the more accurate name of the PS Vita TV. Connects to DualShock 3 or 4 controllers in replacement of the normal Vita's controls. The DualShock 4's touch pad can also be used to emulate the Vita's touch screen and rear touch pad. Very easily identified by it's sleek and small “flat plate” form factor that has no screen. The one obvious benefit of the PSTV is that it allows playing Vita games, homebrew, and other-such software on one's TV. In fact, homebrewing is almost a must for the PSTV, as a large amount of Vita software will refuse to work on the PSTV due to Sony-added limitations that aren't even necessary.
References
https://en.wikipedia.org/wiki/PlayStation_TV
https://en.wikipedia.org/wiki/PlayStation_Vita
https://retrogamebuyer.com/ps-vita-1000-vs-2000/
https://www.reddit.com/r/vita/comments/lw5frh/pros_cons_of_ps_vita_1000_ps_vita_2000/