Watts are watts in regards to heat radiated by light fixtures. The heat comes from the bulb and the ballast with HID. The heat from LED’s is largely from the drivers, with LED’s themselves adding the rest. Still, if you run 500W HID, or 500W LED, heat output remains same. Good discussion.
I forget the exact numbers, but 90% of the power going into a 6 becomes heat, and about half of that leaves as IR radiation. The LED turns about 70% of it's power consumption into heat. Most of which leaves by convection.
This makes putting your hand under a HID unbearably hot at distances you can't really feel anything under the same powered LED