The first is a SATA SSD, which comes in a 2.5-inch form factor and connects to your motherboard with the same cables and ports as a SATA HDD. The second (and newer) is the M.2 SSD.

Western Digital Blue 1TB vs ssd M.2 Samsung 980 Pro 1TB Game Loading Times Ad - 0:00 Games: Forza Horizon 5 - 0:06 Halo ...

The SSD, however, is faster than the HDD at random (non-sequential) disk access. This difference shows itself in "real world" tests such as Exporting a 60MB Quicktime, Compiling an Application or ...