The simple answer is "yes." The complicated answer is:
"Turn out" is only used with some kind of light.
"Turn out" means extinguish a light, make it go dark.
You can turn out a kerosene lamp, but it doesn't make sense to talk about "disconnecting" it.
"Turn off" means to de-energize, to remove power. "Disconnect" is not quite right. Usually you would turn off a computer with the power switch, while leaving the power cord connected. You could disconnect the computer from the Internet, but that does not turn it off. Or, of course, one way to turn off a computer is to disconnect the power.
You can say "turn out the light."
You can say "turn off the light."
You can say "turn off the computer."
You can NOT say "turn out the computer."
I think the word "turn" is used because many gas valves, and many power switches, literally did turn.