Resource files or folders, which is best for Mac icons?
allows you to save icons as either resource files or folders. The best option depends on how you plan on using the icons you are creating:
Save as resource file: this is most useful when you will be incorporating the icon into a application (since the resources can be read by a software developer with Resourcerer.) It’s also a good format to use when you’re not sure how the icon will be used—it shows up on the desktop and can be copied and pasted using Get Info.
Save as folder: this is most useful when you will be creating icons for downloading off of a website. Users are accustomed to having them this way, and any Open/Drop states that you include in the icon will be displayed correctly.