You should find out directly from your buyer(s) what standards they will accept. Some buyers will only accept GFSI recognized standards such as GLOBALG.A.P.
The main difference is that the Produce Harmonized GAP Standards are not recognized by the Global Food Safety Initiative (GFSI) while the GLOBALG.A.P. Standards for produce are GFSI recognized.
The importance is that your certificate should be accepted by all buyers worldwide. The motto is “once certified, accepted everywhere.” For more information about GFSI click here.