Cosmetology (whose root is cosmetic) is the study or art of cosmetics and their use. The job of a cosmetologist is to make people beautiful. Cosmology (whose root is cosmos) is the study of the physical universe considered as a totality of phenomena in time and space. Cosmologists consider vast questions such as the origins and trajectory of the universe, the movements of galaxies, and the nature of space-time.
Cosmetology is mainly an American term, but it has begun to work its way into other varieties of English. Cosmology is used throughout the English-speaking world.
Examples
Modern cosmology theory holds that our universe may be just one in a vast collection of universes known as the multiverse. [The Daily Galaxy]
It was the 1980s when Alicia Garmon, a hairstylist in Georgia, studied hair at cosmetology school. [CNN International]
They strive to produce a likeness, which has long been despised by critics of portraiture as a pedantic substitute for the grander challenges of big ideas, cosmological questions and historical vision. [Guardian]
Last year, the revered physicist and cosmologist suggested that extraterrestrials almost certainly exist but that humans should be taking steps to avoid them rather than seek them out. [Telegraph]
A cosmetologist will teach participants how to enhance their appearance using makeup techniques and how to disguise hair loss using wigs, scarves and accessories. [Suburban Journals]