Both promise to let you play a PC game somewhere other than your desk, and both work by streaming video to a screen instead of running the game locally on that screen. That's about where the similarity ends -- where the game actually runs is a completely different story, and it changes what hardware you need and what it costs.
Steam Link: your own PC, just streamed elsewhere
Steam Link is remote play. The game runs exactly where it always has -- on your gaming PC or laptop -- and Steam Link just captures the video and audio and sends it to another screen: a phone, a tablet, a Steam Deck, a TV in another room, or even a device outside your home over the internet. Your PC does all the real work. Steam Link is free, but it isn't magic -- it only streams a game that's actually installed and running on hardware you already own.
True cloud gaming: someone else's server does the work
Services like GeForce Now and Xbox Cloud Gaming work the opposite way. The game runs on a remote data-center server that Nvidia or Microsoft owns, not on anything in your house. Your device -- a phone, a Chromebook, a browser tab -- just displays the stream and sends your button presses back. Because the actual processing happens somewhere else, your own hardware barely matters. The trade-off is that this convenience isn't free: cloud gaming services charge a subscription (or limit free access to short sessions), where Steam Link costs nothing beyond the PC you already own.
The requirement each one shifts onto you
Steam Link shifts the requirement onto your wallet up front -- you need to already own a reasonably capable gaming PC, and that PC has to be powered on and reachable whenever you want to play remotely. Cloud gaming shifts the requirement onto your internet connection and an ongoing subscription instead -- no home gaming PC required, but a stable connection and a monthly (or per-session) cost become the price of entry.
Which one actually fits your situation
If you already own a solid gaming PC and just want to play it from the couch, your Steam Deck, or a laptop while traveling, Steam Link is the free, obvious choice -- there's no reason to pay a cloud subscription to stream a game you could already run for free. If you don't own a gaming PC at all, or your current one couldn't run the games you want, cloud gaming is the one that actually solves that problem, since it supplies the hardware instead of assuming you already have it.
The option that skips the question completely
Both Steam Link and cloud gaming exist to solve the same underlying issue: a demanding game that needs somewhere powerful to run. Browser-based multiplayer games were never built around that assumption in the first place -- they're designed to run light enough that the device in front of you is already enough, no remote PC and no rented server required.
That's the whole idea behind RivalPit -- 110+ casual multiplayer games that just load and run in any browser, no home gaming PC to stream from and no cloud subscription to pay for.
Frequently asked questions
Is Steam Link the same thing as cloud gaming?
No. Steam Link streams a game that's actually running on your own PC or laptop to another device. True cloud gaming services like GeForce Now or Xbox Cloud Gaming run the game on remote servers you don't own, so your own hardware barely matters.
Does Steam Link cost money?
No, Steam Link itself is free. The only real cost is that you still need a capable gaming PC at home to actually run the games, since Steam Link just streams the video and audio from it.
Do I need a powerful PC to use Steam Link?
Yes. Since your own PC does all the actual game processing, Steam Link only helps you play a game elsewhere in the house (or remotely) — it doesn't reduce the hardware you need to own in the first place.
Which one should I use if I don't own a gaming PC at all?
True cloud gaming, not Steam Link. Steam Link has nothing to stream if there's no gaming PC running the game at home. Cloud services run the game on their own servers instead, so no local gaming hardware is required.