Basis of differentiation

Antibody affinity

Antibody avidity

Definition

The attraction which a specific antibody binds to its corresponding antigen

Is the strength which an antigen-antibody immune complex possesses at that epitope 

Strength

Is comparatively low

Is comparatively high

Mechanism

The strength is generated by a single epitope interaction with a paratrope on the antibody 

The strength is produced by several avidities

Antibody type

Antibodies are monovalent or divalent

Antibodies are multivalent

Specificity

Antibodies require a high specificity towards its epitopes

Antibodies have less specificity towards their antigens