Ok, first of all, the number of wires (one or two) a switch has, has nothing to do with it being a toggle switch, or a push button switch. Both types of switches are equipped with either one, or two wires. Yes, one is latched to keep the switch "switched" and with one flick of a finger shuts down the engine, while the other one must be depressed long enough for the engine to die.
Again, both of these switches can be either single, or two wire switches.
With a two-wire switch, one lead goes to the coil, and the other lead goes to ground. Usually engine ground, but it can go to any clean chrome, or bare metal surface on the entire bike that has no voltage potential with the engine. IE any part of metal anywhere that shares the ground.
With a one wire switch, one lead goes to the coil, and the other lead is actually the body of the switch that is grounded via the body of the switch to the handle bars. It can still be toggle, or push button.
Case grounded switch or insulated switch with the lead going to a second wire is what denotes number of wires, not the type of switch it is.
This was way more words than the subject merits. Here's a finger paint schematic of both types of switches with either wire configuration. Single wire always assumes that the switch case is grounded to the handle bars.