Difference between covalent radius and vander waals radius?

Covalent bond radius refers to half of the distance between two singly bonded atoms of the same element ( homonuclear X-X bond) and is denoted $R_{c}ov$. In other words, it is defined as half the covalent bond length when the two atoms bonded are homonuclear.
van der Waals radius is defined as half of the internuclear separation of two non-bonded atoms of the same element on their closest possible approach and is denoted $R_v$.