i use a diffuser to a) dry my hair when i'm in a hurry and b) get my hair bigger than air drying
when i hair dry it takes a while, so with the weight of my hair my roots dry a little on the straight side so my hair isnt as big. but when i diffuse i get more curl at the root which gets me bigger hair
vs diffuser
but i will add that i use less product now compared to the air dried pic (for some reason i cant find any recent air dry pix) so that plays into how big of a difference. according to my friend there is only a slight difference between the diffused hair and air dried and that its all in my head which could be very true lol