desktop,ios and android script differences??

Here is this from the iOS getting started page:

Unity's iOS and Desktop Targets Differ Statically Typed JavaScript

Dynamic typing in JavaScript is always turned off in Unity when targetting iOS (this is equivalent to #pragma strict getting added to all your scripts automatically). Static typing greatly improves performance, which is especially important on iOS devices. When you switch an existing Unity project to the iOS target, you will get compiler errors if you are using dynamic typing. You can easily fix these either by using explicitly declared types for the variables that are causing errors or taking advantage of type inference. MP3 Instead of Ogg Vorbis Audio Compression

For performance reasons, MP3 compression is favored on iOS devices. If your project contains audio files with Ogg Vorbis compression, they will be re-compressed to MP3 during the build. Consult the audio clip documentation for more information on using compressed audio on the iPhone. PVRTC Instead of DXT Texture Compression

Unity iOS does not support DXT textures. Instead, PVRTC texture compression is natively supported by iPhone/iPad devices. Consult the texture import settings documentation to learn more about iOS texture formats. Movie Playback

MovieTextures are not supported on iOS. Instead, full-screen streaming playback is provided via scripting functions. To learn about the supported file formats and scripting API, consult the movie page in the manual.

And from the android page:

How Unity Android Differs from Desktop Unity Strongly Typed JavaScript

For performance reasons, dynamic typing in JavaScript is always turned off in Unity Android, as if #pragma strict were applied automatically to all scripts. This is important to know if you start with a project originally developed for the desktop platforms since you may find you get unexpected compile errors when switching to Android; dynamic typing is the first thing to investigate. These errors are usually easy to fix if you make sure all variables are explicitly typed or use type inference on initialization. ETC as Recommended Texture Compression

Although Unity Android does support DXT/PVRTC/ATC textures, Unity will decompress the textures into RGB(A) format at runtime if those compression methods are not supported by the particular device in use. This could have an impact on the GPU rendering speed and it is recommended to use the ETC format instead. ETC is the de facto standard compression format on Android, and should be supported on all post 2.0 devices. However, ETC does not support an alpha channel and RGBA 16-bit will sometimes be the best trade-off between size, quality and rendering speed where alpha is required.

It is also possible to create separate android distribution archives (.apk) for each of the DXT/PVRTC/ATC formats, and let the Android Market's filtering system select the correct archives for different devices (see Publishing Builds for Android). Movie Playback

Movie textures are not supported on Android, but a full-screen streaming playback is provided via scripting functions. To learn about supported file formats and scripting API, consult the movie page or the Android supported media formats page.

Hope it helps!

No, I think the android and iOS scripting is the same, so you should be good to go.