Diff words, same -Same
Sata 1 (Really sata 1.5) = Sata 150
Sata 2 = Sata 300
HDDs are backword compatable so that a Sata 2 drive wille work on sata 1, or sata 2.
The interfaces are also Backword compatable so that a Sata 6 (Also refered as Sata III) will support a SATA II HDD
Most of the SATA drives now days are SATA II (300), There are a few SATA III Drives, But I would not pay extra for them - If the same price as a SATA II go for it. May need to connect a jumper to force the drive into SAT II mode. Mechanical HDDs do not benifit from SATA6 except for Burst mode.