Hey there.

The topics covered in BSc botany is same as agriculture like, plant physiology, morphology,biochemistry,biotechnology, genetics etc.All these things are covered in BSc agriculture but in a broader sense.

Where as BSc Agriculture includes, Agronomy,Plant biotechnology, plant pathology, Horticulture,Animal husbandary,entomology,Extention Education, Soil chemistry and many more

BSc agriculture is a very different subject or better you say a field with enormous scopes. Just because it has variety of subjects from almost every field and moreover it helps you to think bigger and find number of ways to choose your career.

And as far as I can say about botany ultimately you will be left with few choices in which you can't make changes.

Hope this helps

Best of luck