What does a fire stick do differently than using the apps on my TV?

I've always wondered what these are for.

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I use a Roku box, in place of cable. I don’t have a "smart" tv, so the Roku has various channels, plus it will connect the apps I have on my phone and tablet (Prime, Hulu, Netflix, Paramount+) to my tv.

My understanding is, the Firestick does the same kind of thing.