A hare is a completely different species from a rabbit. Hares are bigger, with longer ears and hind legs. The biggest difference is in their early life stages. Rabbits are born blind and need weeks before they can survive on their own. Hares are born fully developed and ready to be independent.
Tortoises have more rounded and domed shells where turtles have thinner, more water-dynamic shells. Turtle shells are more streamlined to aid in swimming. One major key difference is that tortoises spend most of their time on land and turtles are adapted for life spent in water.