The main difference between ionic hair dryers and regular hair dryers is that ionic hair dryers release negative ions, while traditional hair dryers release positive ions. If you want to reduce static and frizz, try an ionic hair dryer. If you have limp hair and desire more volume, you're better off sticking with a traditional hair dryer.
Negative ions released by ionic hair dryers (as well as ionic hair straighteners) reduce static and frizz. They do this by breaking down the positive water droplets into smaller particles. This dries the hair faster, which reduces heat damage. It also helps to seal the hair strands and lock in moisture.
When selecting an ionic hair dryer, look for one with a ceramic coating. Ceramic coating helps heat the air more evenly. It also often contains crushed tourmaline, which is conducive to the production of negative ions.