please clarify yourself a bit.
I think you are getting two concepts confused. 4/8way is an option for different types of games. Games like pacman do not have diagnals and therefore you do not want to hit say up and left at the same time. Setting yoru joystick to 4 way prevents this from happening so it is only possible to hit one direction at a time. For fighting games, you want 8 way for obvious reasons. Unless you are playing pacman with your t5 stick, you won’t want to change it to 4 way. I honestly hope you are not playing pacman with a t5 stick.
In case you are trying to play pacman with the t5 stick, I don’t think it can be set to 4 way (because no one would want to). p360s, seimitsus and sanwas can all be set to 4way if you wanna play pacman with one of those.
the difference between sanwa/seimitsu/p360 is all preference. p360 is… uhh… ew, I hate american parts so don’t talk to me about them. seimitsus and sanwas can be compared to the t5 stick. they feel similar except a tighter spring. Seimitsus have shorter throw distance and I think their springs are looser.