What are the differences between Corporate Finance, Capital Markets and M&A?

I guess what I'm asking is what is the structure. Is Capital Markets a broad category with Corporate Finance and M&A within it or do they each stand on their own. I'm trying to learn about the various fields. I had thought I wanted to work in corp fin., focusing on M&A side of corp. fin., but I'm starting to think that's not right. Any information to clarify or expand on this would be great. Also, do you capitalize these when talking in a general sense in an essay. I probably sound like an idiot, but I'm confused. I am interested in learning/working in investment banking at some point, so I'm trying to understand things. If I worked for a I-Bank, how would the above titles possibly be related to departments I could work in. Meaning would I work in corp. fin., M&A, cap. markets, as separate or could they be interrelated?

These are just names of separate departments within an investment bank. Bear in mind, that names can differ among banks but usually this is the case:
Corporate Finance - Raise money in the Equity Capital Markets (ECM). - eg. IPO.
Capital Markets - Raise money in the Debt Capital Markets (DCM) - eg: Bonds, FRNs, etc.
M&A - Mergers and Acquisitions

Sometimes M&A could work with both Corp Fin pple and Cap Mkts pple cos they'll use both financing methods for the acquisition.

You can capitalise as above.