If we compare Surface Pro 6 vs Surface Pro 7 on a timeline, they weren't very far apart compared with the subsequent generations. The Surface Pro 6 was released in October 2018, so it is getting on a bit now, and it's starting to become harder to find deals. The Surface Pro 7 came out just a year later, in October 2019.
It wasn't until January 2021 that the family spawned a new generation in the form of the Surface Pro 7 Plus, an upgraded model aimed only at business customers. That was followed just nine months later by the Surface Pro 8 in October 2021. See how that compares in our comparison of Surface Pro 7 vs Surface Pro 8. Just to make things more confusing, there's also the Surface Pro X – you can read about that in our Surface Pro X review.