If you've had yours for a while, you might have forgotten which model you even have. That's not a problem, though, because it's easy to find out in ... will have a model number.
The two phone numbers on an Apple Watch with GPS + Cellular are relevant ... look for the model number in the Watch app on your iPhone. Search for the model number on the Apple support page to ...
That's not a problem, though, because you can quickly find out your model name and model number in your iPhone's Settings app.