What’s the difference?

Someone in a different sub referred me to this subreddit.

Looking around, all these keyboards seem very aesthetically pleasing and real nice in general.

But what I want to know is this: What’s the difference between the keyboards I see here and one that would, say, come with my desktop?

Sorry if this is a stupid question, I just genuinely don’t know and figured this would be a good place to start. If there’s a better place to find answers, please direct me there!