They’ve always tasted pretty different to me.
(Like Edam, tolerate Gouda but not fond of it.)
They have the exact same ingredients and are made quite similarly.
(not that I’ve personally ever made cheese or know anything about it, but I have spent entire hungover Sunday afternoons witching this guy’s youtube channel. Something so soothing about his voice along with just watching the process.)
I find Edam generally milder and often more soft than Gouda. As noted, I’ve never seen “aged” Edam. I can definitely tell the two apart; I’ve had that blind test done more than once. 