The different types of blender blades differ by their designated usage. The main types are the X and the wing blades.
Food blenders that specialize in soups, sauces, dressings and pastes tend to boast the X style blade. This is better at performing a cutting and chopping function.
Whereas, the wing style is common in drink blenders. The blunter edges are better at crushing ice and pulverizing fruit.
If a blender offers both the X and wing attachments, then this means it will perform a wider variety of functions. This may reduce the need for multiple appliances and save you money and time.