Just guessing here, but I'd say:
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Medical Science is pretty much what it sounds like, you'd study the Science behind medicine (i.e. pharmaceuticals, various equipment, etc. etc.).
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Medical Chemistry would probably focus on the pharmaceutical side of medicine, with you learning all about drugs and whatnot. Probably similar to Medical Science, just with a particular focus on the chemicals involved.
- The B of Science is a general Science degree, allowing you to Major in any of the major studies listed for it
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