Deodorants are products applied to the body, most frequently the armpits, to reduce the body odor caused by the bacterial breakdown of perspiration.

Deodorants work either by using fragrance to cover up malodor or the absorb perspiration that leads to formation of malodor.

Antiperspirants are products that prevent the excretion of sweat which leads to malodor. Products that prevent sweating are regulated by the Food and Drug Administration as Over-The-Counter drugs. As such they must be established as safe and effective according to the standards established by FDA.

A related topic includes Parabens.

Find out for about FDA regulation of Antiperspirants:
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRS...