This is a common question that new Linux users ask and can be quite the rabbit hole to dive down in detail. It can be even more confusing because Linux is often described as Unix-like. So let’s just keep things simple here and if you want to know more I encourage you to keep digging into the history.
First off – are Linux and Unix the same thing? The short answer to that is no, Linux is not Unix and Unix is not Linux.
At it’s core the term Linux refers just to the kernel of the Operating System. Think of this like the engine. All of the software you run on your Linux PC is built to run on top of the Linux engine.
Unix is somewhat similar but in general Unix refers to a complete package, so an engine, frame, some doors a steering wheel and a set of keys. Everything you need to drive the car, navigate to where you’re going and make sure you get there safely. The Linux equivalent to this level of of a complete package is a Linux distribution (like Ubuntu, Red Hat, Debian, Fedora, etc.).
Just like Linux, Unix can also come in various distributions but again there are differences. Generally speaking – again this is very much a simplification – Linux distributions simply package up existing software but they don’t necessarily maintain that software. For Unix, the distribution is often also responsible for packaging up and maintaining the software to ensure proper compatibility. As a result Unix can sometimes be more stable than Linux… but even that is not always true.
The long and short of it is that Linux and Unix should be considered different things even though they share a lot of commonality. That said both are excellent Operating Systems and are used extensively in the real world.