I think those would be categories? Some categories are kind of boring and just say how much of the game to finish, or whether specific glitches are allowed, but other ones are more like their own little “genre”. So for instance, there is the Link to the Past randomizer stuff, which I believe was raced in this AGDQ. Then there are things like low% (usually some variation on “finish the game without picking up any items”), zero% (like low% but also no gold/money/etc. pickups allowed)… and yes, pacifist.
If you look at the various category tabs per game on Speedruns Live, that might give you an idea about what kind of challenges people are doing (at least, on a level of organization/communityness that the article is talking about). At a glance, there’s stuff like “use every single item”, “finish the game without using [super useful/basic item]”, “get [specific ending]”, etc. It’s just that then people aren’t satisfied with just completing the challenge, and move on to… well… trying to complete the challenge faster than before!
On the flip side, there’s also longplay – survival mode, basically. I don’t know whether there is a lot of serious competition with that. In Crypt of the Necrodancer, the game I am most familiar with as far as these sorts of speed things go, longplay is kind of a silly funny thing. It isn’t something you’d really want to watch in a game where it’s possible to survive for a very long time, obviously!