What is the parallel equivalent of a 1000 W resistor and a 1500 W resistor in parallel?
Actually, the question makes no sense.
You need to know the resistance of the two resistors to determine their circuit characteristics. Resistance of measured in Ohms.
The Watt rating of a resistor determines how much power it can dissipate before failing. The heating element in a electric fry pan might be able to take 1500 W. These typically have a low resistance. If you purchase a fry pan in Europe, it might have a higher resistance, but still provide the same 1500 W of heating. Because the European standard for AC power is 220 Volts, a higher resistance is required to achieve the same power output.