Without American equipment, the USSR would not have had the supplies to push the Germans west. Without a Russian front, the UK and the USA might not have been able to dislodge Germany from Europe, and the UK may have fallen [4]. Without Britain in allied hands, it would have been vastly more difficult for the USA to stage D-Day, and they certainly would not have been able to provide the fuel for their logistical needs via the Pluto pipeline [5].
1. https://en.wikipedia.org/wiki/Lend-Lease
2. https://en.wikipedia.org/wiki/Europe_first
3. https://en.wikipedia.org/wiki/Malta_Conference_(1945)
And Italy. After fighting in North Africa, which tied up German resources and scrubs like, oh, one Field Marshal Erwin Rommel.