Examine the size of the tree. Generally, lime trees are smaller than lemon trees. Lime trees grow to be 6 to 13 feet tall. Lemon trees, on the other hand, will grow to be 10 to 20 feet tall.

Look at the leaves. When the flowers are in bloom, the flowers of a lemon tree will have purple blush, while the flowers of a lime tree have white blush. Also, most lemon tree leaves will be larger in size than lime trees, ranging from 4 to 5 inches in length. Most lime tree leaves are no more than 3 inches long.

Smell a leaf. When torn, lemon leafs have a mild scent. Lime tree leaves, however, have a strong lime scent that immediately identifies the tree.

Smell a sample of the tree bark. Carefully break off a leaf and smell the exposed bark underneath. The bark of a lemon tree has no perceptible scent, while the bark of a lime tree has a very strong lime scent.