Cosmetology is the art and science of beauty care. And someone who has been trained in both Art and Science of the beauty care by accredited institute and is licensed by approved board of cosmetology to perform these services professionally for a fee iswould be know as_ a cosmetologist. The license is strictly subject to renewal.
From the above explanation we can now distinguish between professional and non-professional cosmetologist. Not by saying because Mary is a hair care service specialist (Hairdresser) then she is not a cosmetologist.
Or because Kofi specializes in Nail Care service (Nail Technician) then he is not a cosmetologist. It is never true!
Barbers are also cosmetologist. I am surprised cosmetologists in some parts of Africa Countries had misunderstood the above interpretation.