The most important differences between a mast cell and a basophil are their origins, sizes, shapes of nucleus, and their locations in the body.
They are both types of leukocytes (white blood cells), and granulocytes (containing granules), are responsible for similar allergic reactions, and they both are made in the bone marrow - however
- they are derived from different progenitor cells
- basophils are maturing in the bone marrow, and stay in the blood.
- mast cells are leaving the bone marrrow in an inmature state, and are maturing in body tissues, (connective or mucosal), where the stay.
- also differ in size, and the shape of their nuclei.
More info could be found on related links.