Microsoft does not offer stripped down versions of the Office suite. If you buy Word separately or as part of the suite, it is the same product. The only real exception would be the obvious "collaborative" features with the other parts of the Office suite.
You might also want to take a look at LibreOffice before spending money on MS Office. LibreOffice is maybe a little rough around the edges here and there, but it is more than capable enough for probably 95% of people, and it's free.