Zen was the first core design, Zen+ was an enhancement on it, Zen 2 the newest generation. This is analogous to intel chip generations.

Ryzen 3, 5, 7 and 9 are like your Core i3, i5, i7 and i9 - market differentiators.

I agree that when you start looking at the actual model numbers, they're all over the place. Zen 2 laptop products are 4000 series, but Zen 2 desktop products are 3000. I think this was a mistake, personally.