Question

What is the difference between subshell and orbital

Answer 1

All electrons that have the same value for n (the principle quantum number) are in the same shell

Within a shell (same n), all electrons that share the same l (the angular momentum quantum number, or orbital shape) are in the same sub-shell

When electrons share the same n, l, and ml, we say they are in the same orbital (they have the same energy level, shape, and orientation)

So to summarize:

same n - shell

same n and l - sub-shell

same n, l, and ml - orbital

Now, in the other answer, there is some discussion about spin-orbitals, meaning that each electron would exist in its own orbital. For practical purposes, you don't need to worry about that - by the time those sorts of distinctions matter to you, there won't be any confusion about what people mean by "shells" and "sub-shells." For you, for now, orbital means "place where up to two electrons can exist," and they will both share the same n, l, and ml values, but have opposite spins (ms).