WHAT IN THE WORLD OF MARVEL

WHILE I WAS TYPING MY LAST JOURNAL I WAS BROWSING MY COMICS I REALIZED I HAVE TO TYPES OF AMAZING SPIDERMAN COVERS AROUND #200 SERIES AND #300 SERIES. I SAW SPIDERMAN HEADS WERE REPLACED BY UPC. IN TODD MCFARLANE'S ERA, HE HAS SKETCHES IN THE UPC AND HAVE SAME EXACT ONES WITH UPC. I LOOKED ONLINE AND SAW THAT I ALSO HAVE WHITMAN AND NON-WHITMAN COVERS. DOES THIS MEAN ANYTHING? IF I CGC BOTH UPC AND SPIDEY HEAD UPC WILL THEY COME UP THE SAME OR CONSIDERED A VARIANT. DOES THAT ALSO APPLY WITH THE WHITMAN AND NON-WHITMAN COVERS TOO?