Dry brushing and exfoliating are different things.
Dry brushing your skin is better than wet exfoliation because water causes your skin to plump up which makes it more difficult to shed dead skin cells.
When you dry brush your skin you promote the lymphatic drainage and stimulate circulation in your body, which may temporarily reduce the appearance of cellulite.
Although dry brushing is not the exact same thing as exfoliating you can exfoliate your skin by dry brushing and it also promotes healthy, shiny and smooth skin.