Its 600w and watts equal heat. The light you have is only 132w draw so there's a big difference.
You can also use a fan speed controller to lower the air exchange if needed and opt to vent back into the garage if you were venting directly outside it.
Then you also have the insulating methods as mentioned by the knowledgeable dudes above.
I hate to see heaters been used, always seems like watts not going into light is a waste, but then some folks would be screwed without them
I knew there had to be a lighting option to supplement the heat that would work better than wasting 1500 watts on a fire hazard.
Already using a fan speed controller and venting back into the garage in the direction of my intake fan