Hair dryers are used to dry and style the hair, ensuring that the heat keeps the style in the hair. Diffusers are attachments that can disperse the heat from the hair dryer over a bigger area so that hair dries faster and is less frizzy.. The diffuser enhances the natural waves and curls in the hair.
I haven't had or used a blow dryer in a very long time. And I had. Honestly, what made the big difference for me was a good dryer/diffuser.
A diffuser can also be used on naturally wavy hair. Instead of concentrating the airstream on a small area, the diffuser distributes the air more extensively. Waves are enhanced, and the hair is left light and bouncy.