Hello,

Agronomy is a branch of agriculture dealing with field-crop production and soil management.Courses in agronomy address the research and development related to studying plant-based crops. Courses in agronomy include topics such as crop and seed identification; crop growth, production, and management; and crop genetics.

On the other hand M.Sc. (Ag.) Genetics and Plant Breeding includes study of PRINCIPLES OF GENETICS, PRINCIPLES OF CYTOGENETICS, SEED PRODUCTION, MOLECULAR GENETICS, BREEDING FOR DISEASE RESISTANCE, BREEDING FOR CROP QUALITY, GENETIC ENGINEERING AND BIOTECHNOLOGY.

So, as you can see Genetics and Plant breeding is more diverse, vast study but all in all they are somewhere same.. So, you should choose one based on your interest.

I hope this helps.