>>63762875categories are what the streamer is currently playing. you can click that and find other streamers playing it. tags are what the streamers use to define their channels. most use them for memes, but for example you can look up "goblin" and get goblin vtubers just like that. you can combine categories + tags.
the downside is of course you can only use this to find channels currently live.
of course this is all only in the context of twitch. I can barely find shit on youtube these days.