Blade styles refer to the width of the fingerpick blade. They are marked #1, #2 and #3, with #1 being the narrowest for a brighter tone and #3 being the widest, for a warmer tone. #2 is a happy medium and is probably the most popular choice.
There are two blade angles available. Blade angle refers to whether you want the blade straight, or slightly angled. Straight is the standard choice, but the advantage of angled picks is that they allow for a more efficient contact of the blade against the string as you play.