to compare both, you have to have them in the same units
1 inch = 25.4 mm
8.5 inches = 8.5 x 25.4 = 215.9 mm
11 inches = 11 x 25.4 = 279.4
perimeter of US/Canadian A4 = 2(279.4mm+215.9mm)=990.6
perimeter of rest of world A4= 2(210mm+297mm)=1014 (larger)
Area of US/Canadian A4= 279.4mm*215.9mm= 60322.46 mm^2
Area of of rest of world A4= 210mm x 297mm= 62370 mm^2(larger)