Classic versus subscription refer to the payment/licencing period.
Featurewise, the highest package of both categories includes the desktop version of SketchUp Pro, with the exactly same power-user feature set.
Features only differ in the “extras” (which are not incorporated in the desktop client): SketchUp for Web, additional apps.
I agree, the naming is too confusing (Studio may be misunderstood as a more powerful desktop client, however it is a Pro subscription package with extras). I’ll see if I find an honest and complete comparison table.
And shop is the version people can’t use out in their workshop because a lot of people have no internet connection there… Yup, the names are confusion.