SVG can be used to create vector images in Flex.
Components can be used in Flex. These components can be built in Flash and exported or you can even build them via MXML and Actionscript 2.0. This means that the Flash IDE isn’t needed in order to build applications that use components within Flex.
Flex can also use stylesheets for formatting the content of the swf. This is very cool, it will allow for CSS style manipulation of dynamic swf content via Flex.