There is not big difference between flex and flash. Flash is more oriented or specially designed software for designer because they can create anything without using any code. Coding is the advantage for the designer to save his time but he can also perform the same work without coding. Flash provides number of tools for drawing to create graphics or timeline method for changing those graphics according to the requirement. Flash is used to create web ads, banner for websites, banner for social messages, games, and so on. Using Action Script in the flash we can make our design more lively or realistic. The biggest disadvantage of flash is you have to spend countless hours for creating attractive framework for your project or website. It is really a time consuming process.
Flash can be run on browser or as a desktop application. The Flex application is finally complied into Flash application. So, you can use Flex to develop web and desktop application. Flash also runs as desktop application, So, its now possible to create desktop application in Flex and then compile it as Flash desktop application.
Developers are using the xml editing tool to edit the Flex file. File file is based to the xml standard and it is saved as .mxml extension. You can use the Flex SDK to compile the .mxml file into a Flash file. Then Flash file can be run as desktop or web application.