The benefit of deodorant without aluminum is it is less likely to stain clothing. The aluminum compounds in antiperspirants and combination antiperspirant-deodorants react with sweat, leaving a yellow stain. The acidity of antiperspirants may also damage the fabric over time.
Deodorants and antiperspirants are sometimes confused for one another. Deodorant masks body odor and sometimes contains ingredients to kill bacteria. The aluminum compounds in antiperspirants block sweat glands and prevent bacteria from metabolizing the protein and fats some of the glands excrete, which causes the smell. Though some claim that aluminum is linked to breast cancer and Alzheimer's, research has shown no evidence of this link, as of 2015.