Antiperspirants block sweat glands with aluminium salts. Deodorants, natural or conventional, mask or neutralise odour without reducing sweat. Natural deodorants typically use baking soda, magnesium, or plant extracts to neutralise the bacteria that cause odour.
Baking soda is effective but causes irritation in some people. Magnesium-based formulations are gentler. The transition period from antiperspirant to natural deodorant, typically two to four weeks, can involve more odour as sweat glands adjust.