What do you mean by Vander Waal’s radii and covalent radii?

Covalent radius (denoted by r_c) is defined as half of the distance between the two nuclei of the atoms bonded by the covalent bond.

Van der Waal’s radius (denoted by r_v) is defined for atoms present in solid state. It is equal to half the distance measured between two non-bonding atoms of a homonuclear diatomic molecule.

Notice that the distance measured is between atoms of molecules which are not bonded to each other (see figure above).