For what I know there are only two types of connectors: SATA and [B]e[/B]SATA.
The SATA connector has a “L” shape, whereas the eSATA one is stright.
Take a look here and here
The metal clip that some cable have is only to make connection more stable, because to unplug the cable you must press the little clip first. Gigabyte includes these cables in their mainboards.
About SATA3, I don’t know if there is a special type of cable actually