What's the difference between hydrolyzed glycerin and refined glycerin?

Refined glycerin is generally referred to as cosmetic grade 99.5% glycerin, which is USP grade glycerin.

General glycerin refers to 95 concentration glycerin, generally used in industry, 

can not be used in cosmetics and drugs and food industry, of course, 

refined glycerin can also be used as food grade glycerin, used in the food industry,

can also be better as drug grade glycerin, used in medicine. 

Refined glycerol is a general term, and the specific classification of glycerol is: 

industrial grade, cosmetic grade, food grade, drug grade (divided into adjuvant and main drug), 

four grades.