Hello Prajwal...Horticulture and Microbiology are totally different from each other. Microbiology is the study of microorganisms and Horticulture deals with science and technology of growing and cultivating different plants ( medicinal, fruits, vegetables, nuts, flowers, herbs etc.)and non food crops .(grass and ornamental trees etc.)Both the subjects are equally good in respect of job scope. It will be beneficial for you , if you choose according to your aim & interest.

If you go for Horticulture you can find job opportunities in field of Government and Private sectors. You can find scope in the field of irrigation , research area, Agriculture development, etc. Microbiology will offer job in the field Healthcare organizations, Forensic Science Laboratories, pharmaceutical, Environmental Organizations etc.

Higher education will offer higher  designation and higher salary jobs.

Hope it helps.

Good Luck