There are three main types of SSDs to consider. One of which is a SATA SSD that connects to your motherboard with a SATA cable and is mounted elsewhere in the PC. Whilst the other two mount to the motherboard directly, which are NVMe and SATA M.2s. Although both connect to the M.2 mount, they don't have the same speed. As the SATA  one will still use the older, slower controller as the SATA SSD. So NVMe will excel in terms of speed but at a price.