Answer
Clonal selection is determined by factors external to the reproducing cell while Lamarck’s idea of inheritance was determined by factors internal to the reproducing organism.
Work Step by Step
With clonal selection, lymphocytes are selected for only if they do not react to self and matches with its corresponding antigen. Traits are determined somewhat with probability (the development of the antigen receptors) and somewhat with active selection (the destruction of self-reactive cells and the promotion of cells that react to discovered antigens). With Lamarckian inheritance, traits and inheritance are determined by the organism itself.