关于Master of Science与Professional Master of Science的选择

各位大大能帮忙具体分辨一下下面两个master的意义么
Master of Science (M.S.) (Plan I). This plan is used infrequently. If admitted to the Public Policy (M.P.P.) - Mechanical Engineering (M.S.) concurrent program please contact or visit the Student Services Office for requirements.
Professional Master of Science (M.S.) (Plan II). This is a more common option. If admitted to the Public Policy (M.P.P.) - Mechanical Engineering (M.S.) concurrent program please contact or visit the Student Services Office for requirements.
The latter 我觉得应该就是专业硕士吧，为什么这个被认为是一个更加普遍的选择呢？难道大部分人还是偏好读专业硕士？这样的master到底值得读么？国外业界比较偏好哪一个呢