Hi mirrormirror,
I have both products, and my bottles have different ingredients on each. The moisturefuse has more ingredients in it. My understanding of each product is that the Moisturefuse imparts moisture and softness, the Fulfyl adds strength and moisture to the hair. I get different results with each product. The Moisturefuse gives me more slip. The Fulfyl doesn't make my hair as soft, but acts like a mild protein treatment; something like Nexxus Keraphix.
The purpose of heat with any product is to lift the cuticle of the hair and cause a deeper penetration of that product in the hair shaft. HTH /images/graemlins/smile.gif