Fediverse

First of all, how is called this category of programs, instance engine?

Second, why there are 3 different, basically inter-compatible projects out there, what are the benefits of each one over the others? and why does Lemmy prevail all of them.

*i will be using feddit as a umbrella term for all the reddit-like fediverse.

I don't have much of a technical Background to know how this things work under the hood, but I'm quite curious of where all of this is heading.

I see a lot of awesome features locked away in these other projects that would be just nice if it was standard to have them, like piefed's hashtag-like system that allows people to seek things by topic instead of going to a specific community hosted in a specific instance, it would instantly fix the fragmentation problem across feddit, lol.

How the future of feddit will be? will be all be using Lemmy or other specific project, or instances will use whatever project they like and they will be cross compatible enough that it won't be much of a deal what project is running underneath?