check out the different malts and grains at briess website:
http://brewingwithbriess.com/Products/Default.htm
grains also affect flavor, so you need to work it into your recipe. for instance, let's compare 2-row to chocolate malt (two extremes of the range):
The lovibond rating is the color...notice that the chocolate malt is very dark. in small amounts it could add a red to brown color and impart a small amount of flavor. large enough amounts will make it nearly black and impart a huge flavor (too much can definitely be a bad thing with any specialty grain.)
2-row on the other hand is a simple base malt, NOT a specialty malt. nothing has been done to it, it hasn't been kilned or baked or anything to impart too much flavor. it adds a minimal amount of color, and is used mostly for conversion and to create the base for fermentables to create alcohol.
Chocolate Malt
Lovibond - 350
Flavor - Rich, Roasted, Coffee, Cocoa
Description - Use in all beer styles for color adjustment. Use 1-10% for desired color in Porter and Stout. The rich roasted coffee, cocoa flavor is very complementary when used in higher percentages in Porters, Stouts, Brown Ales, and other dark beers.
2-Row Brewers Malt
Lovibond - 1.8
Flavor - Mild Malty
DP 140
(This is the diastatic power...the amount of starches it can convert into simple sugars for the yeast to make alcohol)
Description - Base malt for all beer styles. Smoother, less grainy flavor than 6-Row Brewers Malt. Slightly higher yield than 6-Row Brewers Malt. Slightly lower protein than 6-Row Brewers Malt.
hope that helps. read the website.