Walnut
Walnut
The walnut tree is famous for its (nutty) fruit and beautiful wood.
Is this tree producing any fruit? If so, try rubbing your fingers against one and smelling the oil it produces: it's a commonly used ingredient in soaps and perfumes.
Didn't get this one right? Don't worry! Just like other living things, there's a lot of diversity in the plant kingdom, and even two trees of the same species can look very different from each other. Identification takes practice!