Uh, you've got it exactly backwards; LED conducts and convects heat to the air around itself, whereas light bulbs emit lots of radiant heat, aka infrared, which heats plants directly.
Hold your hand near an HID lamp, you'll feel your hand get warm very quickly. LED doesn't feel like this. Instead there's much more brightness but not so much heat forced at the plants.
To put it another way; the element in an HID lamp shares many similarities to that ceramic bar in your toaster oven. They both make a lot of infrared light, aka radiant heat.
You can't make toast with an LED.