DD creams are where it gets a little tricky, as many brands have different definitions for this category. Generally, DD creams tend to do "double duty" (and then some) — coverage, anti-ageing, sun protection, etc. Now, are DD creams really that different from their double-lettered counterparts? It depends on the brand. Ultimately, you'll have to play around with the formulas to figure out which one makes the most sense for you and your needs — and not focus too much on their position in the alphabet.