I have used both of these heat protectant products, Dove was the first "spray" for heat protectant I ever used back when it came in a orange bottle with a slightly different formula. But originally the first heat protectant I used came from Tresemme, it came it a squeeze bottle in a gel form it was from the same thermal creations line as the spray comes from.
I am currently using the Dove Heat Defense Protect & Shine Mist. Dove recently changed the formula for their heat protectant spray to a weightless formula with mirco moisture serum. It does seem different from the first form of the spray. Definitely weightless as long as you don't use it in excess. You only need two pumps at the least all over. I really like the smell of it and the sleek bottle.
The Tresemme Heat Tamer Spray is probably the most popular at the drugstore. It comes with a squirt nozzle pump which lets you control the spray a little. I feel like this weighted down my hair a little bit and made it sticky at times, Maybe I was using too much? But I think it gets the job done as well.
I really like both of these sprays, they work well. I probably slightly prefer the Dove one. they are both equally comparable in protecting your hair from heat damage.