Just call it "Lemmy".
Call Mbin, Piefed, and Friendica "Lemmy-compatible".
I thought about this for a while. Just tell the masses to try Lemmy. It's the most polished and the easiest to understand.
More techy users who want more can consider other Lemmy-compatible software. There's Mastodon-compatible software like Sharkey and Iceshrimp but we generally associate microblogs with Mastodon. So, generally associate communities with Lemmy.