Mac OS X Yosemite will come with a bunch of new interesting UI updates. The updates includes icons and just as iOS8 started a trend, this update to Mac OS X will probably also be defining a style for desktop app icons. Jim Tanous did a nice side-by-side comparison of the icons. Regarding how Apple clearly hasn’t settled on a streamlined OS X icon style, despite iOS now having a very well defined “framework” for icons.
The icons above are property of Apple Inc. Duh.