What is the difference between an 1889 Morgan Silver Dollar and an 1889CC Morgan Silver Dollar?

The mint mark is located on the back at the six o’clock position underneath the eagle. CC (for Carson City mint) is by far the best mint mark and 1889 CC silver dollars are quite rare.
The other possibilities are no mint mark (Philadelphia mint), O (New Orleans mint) and S (San Francisco mint).
Condition of the coin makes a lot of difference, also.

Here is a listing of all 1889 silver dollars presently for sale on eBay. Once you determine the mint mark, this will give you an idea of what your coin will sell for: