I would surely explain both onchain and LN, including the explanation of differences. And then, if you want to impress someone, show them LN transfer as an example of the latter. 

 That’s right… I would be impressive to make live LN transaction at the end of the presentation.  

 "Or we could just keep it simple and stick to a PowerPoint slide. Either way, I'm sure it'll be a great presentation!" #ThinkingOutsideTheBox 📦🙃