As jsenske has already written, you can't go wrong with an NVME SSD, but there are also differences here.
The 970 Eva is a little older and is based on PCI-e 3.0, but if you have a board that supports PCIe 4.0, the 990 is faster.
Samsung 990 EVO (2000 GB, M.2 2280)

You also have to bear in mind that with 1TB for os and documents, 256GB are quickly gone and the games are also getting bigger and bigger, so the question arises as to why not buy a 2TB ssd right away.

The M.2 SSD generally speeds up work on the PC, including gaming of course. The 970 EVO Plus is a good choice. I am very satisfied with this SSD.