A masters degree in a specific field prepares you for a career with specialization in that field. You can expect to spend your career applying what you learn, extending your knowledge in the field through experience, and advancing in that field. The masters degree gives you a high concentration in the subject.

An MBA degree prepares you for a management position in a business. It is a broad degree, with relatively little concentration in one subject. You take subjects in accounting, finance, marketing, organization behavior, quantitative methods, and other subjects such as human resources, real estate, insurance, etc. The degree trains you to take charge in any managerial position and advance to the top managerial level in a corporation. The combination of a science or engineering degree and MBA is highly desirable, because companies need managers who are conversant in the science area as well, so that they can communicate with the scientists that they have to manage. MBA degrees are sought by professionals in medicine, law, various sciences, music, literature, history, political science, and others. A physician with an MBA eventually may become manager of a hospital. A musician is able to manage the business affairs of an orchestra or opera company. The English major may wind up managing a publishing house. You may get a managerial position with a high tech company.

A lot depends on your goals. If you want to concentrate on your science, get the Masters. If you prefer to advance in management, get the MBA. Both degrees are valuable.