Differences of the Different Doom 'Standards'?

I don't give a fuck should be the standard, running around with "I don't have permission and it's immoral" in my head is ridiculous, I read that crap over there too, when I first started messing with maps four years ago over there seeing "them" pick apart someones good work because certain textures don't belong in certain places set me off and fuck the re release (drops mic)

Basically, it's like this:
Vanilla - can run on the original dos .exe; has tight limits on visplanes (distinct visible floor/ceiling heights/textures per any vantage point), excessive linedefs within field of view lead to hall-of-mirrors effect. (linedefs are broken up by the engine into 'segs' which is the relevant term for this limit)  Dehacked (.deh format; think .bex is a later expanded thing for ports) patches can be used, but must be applied directly to the binary (.exe) itself if using the original binary.

Limit Removing - same as above, but with the limits massively increased to the point where they're probably not going to be an issue. generally supports dehacked patches (deh and bex) being applied to internal game frame/data tables in a controlled manner, in a convenient way. must be run in a source port.

Boom - early sourceport expansion, most importantly adding Generalized specials which allow combining various effects into one so you can apply multiple effects at once. Very widely supported.

MBF - further iteration of above, not as widely-supported.

Hexen - differing map data due to stuff like polyobjects and additional thing fields. OG Hexen itself basically mostly ditched line/sector specials and almost everything is done via ACS scripting. much less convenient and a bit more time-consuming, but raises possibilities (speaking particularly about Hexen here). Supported to one degree or another by some ports, including of course 'Doom in Hexen' format, which I'm pretty sure retains original line and sector specials. Off-hand, I'm really not sure to what extent ACS scripting and Hexen format are tied together outside of Hexen specifically.

DECORATE - introduced at some point by ZDoom. basically something like a saner take on dehacked patching (never used it, myself.) A few different ports support it to one degree or another.

... bunch of different things go here intrinsic to other ports, like Vavoom C, DDF, COAL, EDF

GZDoom - basically a big pile of possibilities; ZDoom became the most popular engine for extensive modding, and GZDoom inherited this momentum and built upon it. ZDoom and GZDoom both tweaked Doom gameplay somewhat arbitrarily in various ways which bothers some. Examples include higher-precision/fixed physics which eliminated tricks like wall-running, default removal of 'infinite height' of doom actors, etc. It's a distinct experience.

More detail can be found on Doomwiki.org, but this should cover a fair bit. There're also the later iterations on Dehacked like DSDehacked and the MBF21 stuff. The most popular formats are, in no particular order, Vanilla, Boom, and GZDoom's stuff. I haven't kept up with/ really paid attention to MBF21, but it's probably also used lately. ID24 is the new 'official' thing which I don't think is actually fully implemented by anything, yet, and its actual future is currently in question.

Theres a pretty small subset of players who are willing to change away from the doom source port they've configured for their optimal doom experience.

point being you can pick a mapping format based on what features you plan to work with, but the closer you work to vanilla will likely yield most exposure (e.g. more potential players)

Something funny that I didn't see people mention too much is that neither the new port nor the ID24 standard are even Vanilla. The new port isn't demo compatible, something that even the Unity port managed to do, and the reimplementations of Boom and MBF aren't accurate. It's like they hired Graf Zahl, took a few GZDoom features and asked explicitly vanilla ports to implement it.