Which would be better? More employable? Better salary? I am planning to go to grad school, which one is more focused? Which grad degree study area would each degree fit better with? Is a double major in these good/worth it?
The name of your major doesn’t really matter for graduate school, when it comes to closely related majors. Your research experience, research interests, and fit with potential faculty members at a particular graduate department do.
The kinds of work these tend to lead a graduate to are different (I have seen from Indeed.com searches). Environmental science tends especially to open doors to field inspection and ensuring regulatory compliance. Environmental chemistry tends to lead one into work in analytical laboratories.
I would say that majoring in Environmental Science constitutes majoring in the environment, and majoring in Environmental Chemistry constitutes majoring in chemistry with a little environmental flavor.
For best value in education for an environment protection related career, I believe taking any available courses in environmental regulations and in environmental analytical chemistry - those two are the jewels - is more important for having good job prospects later than whether you major in Environmental Science or Environmental Chemistry.
From my experience of many years working in them, it’s easier to get a job in environmental chemistry laboratories with a bachelor’s in chemistry than with a master’s in chemistry. MS-holding applicants seem over-qualified and are avoided.
The surveys at payscale.com indicate the ranges in salaries for a BS and an MS both for chemistry and environmental science are quite large. The middle of the Chemistry BS range there is about the same as that of the Environmental Science MS range.
Today on the jobs website Indeed.com there are 4,221 results for a search of ‘Environmental Scientist’, 740 for ‘Environmental Chemist’ and 10,146 for ‘Chemist’. An environmental chemistry degree emphasizing analytical chemistry would make available to you many lab jobs outside of, as well as inside, environmental analysis.