Stumbled across this CensoredGaming Twitter post about the game Waifu Uncovered: https://twitter.com/CensoredGaming_/status/1333560403809476610
The game, developed by One-Hand-Free Studios, is a shoot 'em up where the background contains an anime girl -- sorry, I mean waifu -- and you're tasked with shooting off all clothes.
It's available on Steam (reqiures login and allowance of adult content in account settings) and Nintendo Switch.
The physical release supports "censored, uncensored and fully uncensored" modes while the digital version do not include "fully uncensored" (and only censored in the Japanese version).
EastAsiaSoft is publishing the Switch version and they've been involved with a number of niche games like recent PS Vita ports.
Interesting business model if there's enough demand, with cartridges priced at $35 + shipping while digital distribution is $5 or under.
For the Switch a physical release is mandatory for full uncensorship as Nintendo won't support adult content on their digital platform.
Does Witcher 3 show genitals? I assume that'd be the difference.
Edit 1: I haven't played either game, I'll try to confirm my suspicion.
Edit 2: Here's the ESRB rating: https://www.esrb.org/ratings/33771/The+Witcher+3%3A+Wild+Hunt/
No penis nor vagina. But it's a good clarification, since that's 1 difference between Mature and AO, with the latter AFAIK being completely avoided.