Are we just playing "rile up the beer snob" now?
There is no such thing as "stout-porter." They are distinct styles that are both dark. Guinness is (imo) the quintessential dry Irish stout. You could even make an argument that dry Irish is the default stout style, so it's the quintessential stout.
As for porters, Black Butte for the American style that is roastier and more similar to stouts than the British version, and Samuel Smith's Taddy Porter for the British version, which leans a bit more towards the brown ale side of things, and tend to be a little funkier than the American version.
There's a good rundown of beer styles
here.