A look at the dictionary informed me that corned beef is brined/spiced beef. Pastrami, on the other hand is smoked/spiced-seasoned beef shoulder. Do you Chowhounds have any more specific insites into the methods and origins of these two deli & sandwich favorites. I think in many people's minds, the two are very similar.
Growing up in a jewish home in Brookline Massachusetts, i was always under the impression that corned beef was big and chunky and gross and you ate it with potatoes and cabbage until you started gagging and your dad got mad at you, and Pastrami was sliced thin and served on Rye with lots of mustard at the deli where you would go every sunday for bagels and chopped liver and kasha varnishkas.
But that is just my childhood recollection of basically eating something that always tasted to salty for me to handle when i was 10.
There was an awesome article written in Gouret last year all about the finer points of Pastrami and what makes it what is is.
Zingerman's Deli in Ann Arbor has amazingly great pastrami which is fairly similar to their Montreal smoked meat, and different from the pastrami I've had everywhere else. Specifically, I'd say it was more smoky, less salty and more complex. Also, the meat was brown rather than pink. If you ever get to Ann Arbor and you want to try their pastrami, get a #9, pastrami with grilled onions (I remember the number of the sandwich, and I haven't been there for more than two years, so that should tell you something). Or just pick a random number. They don't sell bad food there.
Here's a quote from "SJ's Winners, An Exceptional Approach to Round-the-World Wining and Dining in the San Francisco Bay Area," Serena Jutkovitz, Russian Hill House Books, 1982: " ... pastrami has both etymological and culinary roots in Romania. When American Jews adopted the practice of spicing then smoking meat, beef replaced the pork and lamb more commonly used in the old country. ... Jewish deli corned beef is made by pickling brisket of beef."
Hope this helps.
Historically, I think pastrami is more of a ham substitute...salted or brined, then smoked to cook. If you can get to a smoker (or have an adaptable barbecue) you can put a flat cut of corned beef on the grill, and smoke for at least 8 hours at a temp around 200. Let cool, and cover with cracked black pepper. Wrap in plastic wrap, then foil, and keep in the fridge for 2 or 3 weeks. If you wait until March, you can stock up on corned beef.
From eating at a lot of hofbraus around the Bay, where the meat is sliced right in front of you, I've gotten the impression that in hofbraus, anyway, corned beef, pastrami, and barbecued beef are all different preparations of brisket. That's maybe why hofbrau pastrami carries a decent amount of tasty fat, as opposed to the ultra-lean, beef shoulder, deli slices.