Welcome to Unity!
Please look at this page for how to post code nicely on the forums, for future reference: Using code tags properly
It’s good that you began with some tutorials. That’s a good start.
The reason they are a bit different, is the first piece of code is setting the angular velocity which will continue during play. It can be modified by other forces, or angular drag, though. This is using the physics system, and works with rigidbodies.
The second code example is modifying the rotation a little at a time, each frame and using the transform (rather than the rigidbody). It’s not using the physics system.
Hope that helps some 