When does molecular breeding give an important advantage over conventional breeding, and how can we exploit this?

molecular breeding accelerates the times for genetic improvement  

Explanation:

Molecular breeding refers to the techniques used in molecular biology to improve phenotypic features in plants and animals of agronomic and economic interest. Molecular breeding involves many diverse molecular techniques which include, among others, selection assisted by molecular markers (MAS), genome editing techniques (e.g., the CRISPR-Cas genome editing system), quantitative trait loci (QTL) mapping, gene introgression assisted by markers, etc. These techniques can dramatically accelerate breeding programs aimed at improving plant/animal traits and, therefore, they have a fundamental advantage with respect to conventional breeding methods.

there's no big difference.

explanation:

the only little different between a rabbit and bunny is just that bunnies are much smaller than rabbits. bunnies are basically baby rabbits.