Amaro & Vermouth

What is the real difference between vermouth and amaro?  The lines blur because of the Italian connection and the bitterness factor, but the most outstanding difference is that vermouth must be a minimum of 75% wine, while wine content is optional for amaro.  Amaro and vermouth are both flavoured with botanicals and spices, their popularity is growing steadily and both categories offer a multitude of options for making great cocktails.