Is SDS-PAGE a type of gel electrophoresis?

Yes, SDS-PAGE is a type of gel electrophoresis. 

SDS-PAGE (Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis) is a high-resolution gel electrophoresis technique used for separating macromolecular proteins between 5 kDa and 250 kDa in size. In this method, proteins are separated based on mass. The medium used is a polyacrylamide-based discontinuous gel. The main difference between SDS-PAGE and gel electrophoresis is that SDS-PAGE is used mainly for protein separation while gel electrophoresis is used to separate DNA, RNA, and proteins. Another difference is that SDS PAGE gives a better resolution than the regular gel electrophoresis.