IHO I think that steam infuses more moisture in the hair, then a regular dryer. My last stylist used steam treatments to help nurse my hair and scalp back to health; both were extremely dry. I started to notice that my scalp was no longer itchy and flaky it started to produce oil. I love steam treatments, and for me they proved to be better deep condition.
Steamer conditions faster and seems to make the conditioner penetrate better. Under the dryer, I have to sit for about 45 minutes to an hour for the same results that I get using a steamer for 15-20 minutes. Also, when I use the steamer and then dry and straighten my hair, it doesn't get frizzy as fast and stays moisturized longer. Unfortunately my steamer broke .
The dryer is more versatile because I can use it for drying my hair and deep conditioning even though it it takes a longer.