The developers of Construct 2 do their best to ensure that the features offered work for as many platforms as possible.
But, each platform has additional features that you can add specifically for that platform. For example, when I export games to Windows 8, I detect whether or not the screen is in the snapped or full-screen mode, which no other platforms have.
When you try to add objects to a layout, there is a special section dedicated to only platform-specific features. You will have to add a plugin in order to use them.
<img src="http://simplyadvanced.net/dev/construct2/examples/c2-platform-specifc-features.png" border="0" />
Most other plugins/features you can assume works for all platforms, but you should definitely test everything before publishing.