There really is no comparison, Tildes has a few hundred to thousand active people (looks like about 20 posts a day… across the entire site), and is run by a single guy with very particular ideas about what people are allowed to say and do on his site.
Lemmy meanwhile has roughly 50k users and I would guess hundreds to thousands of posts per day, even if not millions like Reddit that allows more niches to develop.
The Threadiverse is terrible when it comes to news, and niche content. Though as you say Reddit is terrible to actually try to converse with someone on, or even to read through the comments section is like listening to eight year olds (of whatever physical age).
I too go back to Reddit when needed lately, though in read-only mode.