For both of those schools you should consider location first. Would you rather live in Vermont or North Carolina? Neither of the schools are elite and odds are if you go to Vermont you will end up living in Vermont after graduation. If you go to Campbell you will end up living in North Carolina after graduation.
If you truly want to do environmental law then I suppose Vermont is the best option although I have no idea what U.S. News does to determine specialty rankings. Their system for ranking schools generally makes no sense, a judge in Texas fills out a scantron of 1-5 to determine whether Vermont or University of South Dakota should get the 102nd best spot. That system does not make a lot of sense to me and I am guessing the specialty rankings are based on the same methodology. However, considering Vermont does have that specialty ranking I imagine they offer a lot of courses in Environmental Law, which if you have a sincere interest in environmental law would be worth the extra money.
One thing you stated is something all 0L's think that they will get good grades and transfer. To transfer you basically need to be in the top 20% of the class and there is an 80% chance that won't happen. 100% of students on the first day of class think they will be in the top 20%, but you don't need to be a math major to see how that plays out. Don't attend any law school thinking you will transfer odds are you will be disappointed. It is nothing against you, but basically everyone at any ABA law school is hard working, smart, and motivated, and only 20% of these people can be in the top 20%.
Both are very expensive as are all law school, but if you have a sincere interest in Environmental Law and would not mind living in Vermont then going to Vermont is probably worth the extra money.