Hey guys.

My hardware teacher asked our class a question, he asked to explain us what the difference was between keyboards with a 6 pin connector and a keyboard with a 4 pin connector. Can anyone help me with that? I've already did some research and replied him already with the PS/2 connector and Apple Desktop Bus connector.
Here something that might shed little light

shows pictures and little info on all connector types from
pin types 3 - 9

Yeah, I've already looked at that but it doesn't really give you any information about what the difference between those is.
Something like this?</a href>
In response to Tensa Soul
It was helpful but no information on why some keyboards have a 4 pin connector.