A WRT app is basically an HTML file with JavaScript + whatever additional files (such as an image) you need.
Flash is Adobe's tool/run-time. Flash Lite is a subset of "full" Flash and supported in various versions on various mobile phones. See
http://www.adobe.com for more.
If you embed Flash (Lite) in a WRT app, the phone also needs to support Flash (Lite). I.e., it needs to have a built-in Flash (Lite) player and it must be integrated with the browser environment wherein WRT apps run.
If you make a WRT app (.wgz file), you call it a WRT app. If you make a Flash (Lite) app (.swf file), you call it a Flash (Lite) app.
A WRT app could embed/include a Flash Lite app (.swf file).