Reluctantly pushing food to the side for a moment, and turning to that which makes a pub a pub...
Stout: A kind of strong dark beer brewed with roasted malt or barley. Stouts are traditionally the generic term for the strongest (stoutest) of beers at 7% or 8%.
Dry Stout: Dry Stout is Irish Stout is Guinness.
Porter: Not going to talk about porter. It seems to start arguments.
I had to do some research on the word "dry". I remember when it was the fashion for American breweries to make "dry" versions of their beer, but I never investigated what it meant. It did taste different. It didn't last long in the American market.
If stout is called that because it is strong (high in alcohol content) then that can only be achieved by fermenting longer.
Dry is not necessarily stronger, because dry refers to the addition of more hops to produce more bitterness or more of a bitter aftertaste. (Bitter is good in beer.)
Guinness: A famous Irish brewry. Their product.