Alaskan malamutes are bigger and stockier than huskies. Their tails curl over their backs. Their ears are shorter and rounder than a huskies. Generally they don't have blue eyes, although it can happen (it is a disqualifying fault though). Their coat is also generally more plush than a husky.

Alaskan Malamute standard

Size, Proportion, Substance
There is a natural range in size in the breed. The desirable freighting sizes are males, 25 inches at the shoulders, 85 pounds; females, 23 inches at the shoulders, 75 pounds. However, size consideration should not outweigh that of type, proportion, movement and other functional attributes. When dogs are judged equal in type, proportion, movement, the dog nearest the desirable freighting size is to be preferred. The depth of chest is approximately one half the height of the dog at the shoulders, the deepest point being just behind the forelegs. The length of the body from point of shoulder to the rear point of pelvis is longer than the height of the body from ground to top of the withers. The body carries no excess weight, and bone is in proportion to size.
Siberian Husky standard

Size, Proportion, Substance
Height--Dogs, 21 to 23½ inches at the withers. Bitches, 20 to 22 inches at the withers. Weight--Dogs, 45 to 60 pounds. Bitches, 35 to 50 pounds. Weight is in proportion to height. The measurements mentioned above represent the extreme height and weight limits with no preference given to either extreme. Any appearance of excessive bone or weight should be penalized. In profile, the length of the body from the point of the shoulder to the rear point of the croup is slightly longer than the height of the body from the ground to the top of the withers. Disqualification--Dogs over 23½ inches and bitches over 22 inches.