Thank you for your questions and congratulations for your decision to pursue a technical discipline with an interest in Environmental Science. Let me first provide some specific input relative to the difference between an ME program and an MET program.
Mechanical Engineering (ME) programs and Mechanical Engineering Technology (MET) programs differ along dimensions such as focus, coursework, and post-graduate career focus. The focus of ME programs is to provide the knowledge necessary to design and manufacture products and systems needed to meet the current and future needs of society. In contrast, MET programs focus on applying current knowledge and practices to the solution of specific technical problems. Regarding coursework, ME programs require a more extensive background in science and mathematics than do MET programs. Graduates of ME programs are referred to as engineers, whereas graduates of MET programs are referred to as engineering technologists. ME graduates likely seek entry-level positions in conceptual design, systems engineering, manufacturing, or product research and development. MET graduates likely seek entry-level position in product design, development, testing, technical operations, or technical services and sales.
A more detailed comparison of the two paths/degrees can be accessed on the American Society of Manufacturing Engineers website: http://www.asme.org/groups/educational-resources/engineering-resources/mechanical-engineering---mechanical-engineering-te.
You would be able to have an Environmental slant with either an ME or MET focus. The ME program will potentially provide more opportunities given its stronger science and math background. You would be classified as an engineer verses an engineering technician. The latter would probably focus more on testing and lab work. I would encourage you to investigate potential career paths for each degree to determine which path allows you to reach your ultimate goals. Best of wishes, Danielle.