Imperial Porter?

You are not wrong, but beer is what the brewer calls it.

 

When you end the debate about the difference between stout and porter, then start this debate.

 

Hello. You are probably technically correct, but when it comes to names of styles or categories, one brewer's porter is another brewer's stout. A brewer can make an IPA and call it a Double Ale or make a Barleywine and call it a Strong Ale, etc. And specially in the case of porters and stouts the terms are almost 100% fully interchangeable.

 

All I know is, I have a chocolate stout homebrew recipe that tastes just like a porter and it used to bug the hell out of me! Then I realized categorically, there's not a witches tit difference in the two styles!

 

Historically, stout was a stronger version of a porter (a "stout" porter). Today, that historical distinction is still used by some brewers (see Sierra Nevada's Porter and Stout), but in many cases they are used interchangeably, as in the case of labeling something an imperial porter.

 

More in the case where a brewer made two strengths, the stronger one would normally be named a Stout.But many beers such as Guinness were given different descriptions at different times.When shortages/taxation reduced the strength of beers in the UK the stouts were discontinued but the porters were still brewed.These were then simply rebadged as Stout.