What is the difference between a bone bruise and a bruised toenail?

Lots!: Bone bruises are actually contusions that cause swelling in the bone itself. A bruised toenail is otherwise referred to as a subungual hematoma. Nails grow from the nail matrix which is part of the skin.

Anatomy: Bone and toenail are different anatomical structures. Therefore it is just a different structure affected. A bruised toenail will often accumulate blood under the nail which can be drained and the pressure or discomfort relieved quickly whereas a bone bruise sometimes takes as long as a fracture to heal.

Not related: A bruised nail will usually have blood under the nail causing it to be discolored. A bone bruise is a deep injury involving the bone.