What’s the difference between a wallaby and a wallaroo? Both are related to kangaroos. The most obvious difference between the two marsupials is their size. Wallabies are the much smaller species, standing between 12 and 20 inches tall and weighing up to 15 pounds. Wallaroos, however, can stand up to 5 feet tall and weigh up to 120 pounds. Like kangaroos, both wallabies and wallaroos are pouched mammals and use their strong back legs and large feet to hop, jump and leap around.