The 2 different 110 plugs indicate different amperage on the circuit and also should indicate the wiring in the wall as well.
The standard household outlet is for 15 amps max.
Very few kilns can run on such a small amount of amperage.
Household voltage kilns usually need a 20 amp breaker and circuit.
Don't just change the 15 amp outlet to the 20 amp outlet willy-nilly : the wiring from the panel to that outlet may only accommodate 15 amps max.
By pulling more amps than the wire can handle you are asking for trouble, like big trouble, like a fire.