What is the difference between GDUFA and PDUFA?

Both GDUFA and PDUFA are US FDA’s User Fee programs, which help FDA to hire and retain sufficient numbers and types of technical and scientific experts to   efficiently conduct reviews of human drug applications (NDA and ANDA) and improving the predictability of review processes. GDUFA is related to ANDAs whereas PDUFA is related to NDAs. 

GDUFA: Generic Drug User Fee Amendments. The Generic Drug User Fee Act is a law designed to speed access to safe and effective generic drugs to the public, and reduce costs to industry.

PDUFA: Prescription Drug User Fee Act is a law passed by the United States Congress in 1992 which allowed the Food and Drug Administration (FDA) to collect fees from drug manufacturers to fund the new drug approval process.