I am trying to change a thermostat from Goodman HPT 18-60 to Honeywell RTH6300B, but having a trouble to understand the wiring.

The old thermostat has connected with six wires: yellow, green, white, blue, red, and orange.
Y = yellow wire
G = green wire
W2 = white wire
R = red wire
O = orange wire
C = blue wire

The new thermostat needs only five wires and the letters on it are following.
G, W(O/B), Y, R, and Rc

I understand that the yellow wire goes to Y, the green wire goes to G, and the white wire goes to W. I do not need the blue wire, because the new thermostat operates by the battery.

My question is where the red and orange wires go to.

Does the red wire connect to R or Rc? What is the different of R and Rc?

Thank you for your help.
Ryu

The new thermostat is not compatible with a 2-stage heat pump system, which it appears you have. Sorry, back to the store...