I don't know about the american revolution, but that's wrong for the french revolution. I'll link to french wikipédia pages since they are far better on the subject. https://fr.wikipedia.org/wiki/%C3%89tats_g%C3%A9n%C3%A9raux_... Here we can see the first National Assembly was half nobility and clergy. The third estate was the other half.
https://fr.wikipedia.org/wiki/Tiers_%C3%A9tat > Par ailleurs, les députés du tiers état aux états généraux représentaient essentiellement la bourgeoisie[2].
Which indicate that the majority of the third estate representative were bourgeois.
The bourgeois are the middle class.
> The bourgeoisie are a class of business owners, merchants and wealthy people, in general, which emerged in the Late Middle Ages, originally as a " middle class" between the peasantry and aristocracy. They are traditionally contrasted with the proletariat by their wealth, political power, and education, as well as their access to and control of cultural, social, and financial capital.
https://en.wikipedia.org/wiki/Bourgeoisie
Today the meaning of bourgeoisie, still applies to "business owners, merchants and wealthy people", but is now seen as upper class.
I recommend the book "The Men Who Lost America: British Leadership, the American Revolution and the Fate of the Empire"