Hello dear aspirant

Hope you’re doing well

Scope or job options after M.sc zoology is -

1. Conservationist
2. Environmental Consultant
3. Herpetologist
4. Veterinary Technologist
5. Wildlife Educator
6. Wildlife Rehabilitator
7. Zoologist

The scope or job options after M.Sc environmental science is -

Environmental scientists
Environmental Consultant
Wildlife Journalist
Wildlife Conservationist
Conservation Hydrologist
Lecturer

Doing M.sc environmental sciences would be little more beneficial for you than M.sc zoology. Because the former has better and more job options.

Rest, its upto you, do what you feel is better for you

All the best