Skeumorphic design is based on items in the real world. A designer attempts to recreate an object, a clock, for example, and seeks to make it look true to life (3D) with shadows and highlights and such. Flat design, on the other hand, is much more simplistic. It does not attempt to make items appear 3 dimensional and true to life. For example, a simple flat envelope, might stand for mail. Flat designs are as their name suggests, flat. The goal is to convey meaning in a simple, clean, uncomplicated way.
Personally, I don’t have a preference for one design style over the other. The article by Austin Carr, explained well enough the differences between the two design styles, however didn’t provide enough explanation for why flat design was preferred over skeumorphic design. Some designers were quoted in the article who preferred flat design, but for them to just to say they found Apple’s visual references to real world items, like a wooden bookcase and a desktop calendar with leather binding at the top, confusing and unnecessary, didn’t mean much to me. In the second and third articles, however, explanations were given as to why flat design works better than skeumorphic design. The most compelling reasons that caused me to give more consideration to flat design versus skeumorphic were that “it makes for speedier pages, cleaner code, and easier adaptability.” Another point, that having both flat and skeumorphic items in a design, as in the example in article two with the skeumorphic vault and the rest of the web page being flat design, is inconsistent and leads to the design not flowing because of such opposite design methods. I think in some cases the two can be combined and still create a cohesive design concept, but I’m sure there are also times when the two cannot be combined in a way that blends the two together in a way that looks and feels right. I think that would just have to be decided on a case by case basis.