They are all basically the same species, but have differences. Some have higher alcohol tolerances, some bring out fruity characteristics, some are more neutral, etc. This link explains all the strains and what they do: http://winemaking.jackkeller.net/strains.asp
I've used montrachet, cotes des blanc, champagne, premier curvee, and some Lalvin k1-v1116, depending on what I'm making.
Go to http://www.eckraus.com and look for yeasts in the lower right of the home page. Check out the Lavlin yeasts, for starters.
This will not be a scientific treatment of yeasts and strains, but it will tell you what kinds of wines various yeasts are good for. That is, whether it's good for fruit wines, or wines from concentrates, sherry or port, or--like champagne yeast, something with high alcohol content.