To sum it up in a general sentence fauxstrami is what you get when you make pastrami using corned beef on a smoker vs making pastrami the traditional way. Taking a hunk of corned beef, rinsing, rubbing, then smoking will produce a product that is darn tasty and pastrami like however it is not actual pastrami. Hence the term fauxstrami. It is however a VERY tasty treat that I encourage any who own a smoker make at lest once. One look at the ops pics above should be enough to convince anyone to try it. Google the word fauxstrami and you will find the term used over and over again along with many methods + recipes to try on the many smoking and bbq forums. You may even stumble across a post or two from me in those forums while you are at it.
The process for making corned beef vs pastrami are similar how ever they are indeed different. While corned beef is made using the famous brisket cut most pastrami is traditionally made using a beef naval cut. Pastrami is also made from the brisket cut by some and even from a round cut by others. Corned beef is simply cured in a salt brine with some curing salt added (gives the red color) along with spices such as bay leaf, coriander, and such. Most use just a basic pickling spice. Pastrami is cured either via a brine or in some cases such as at the famous Katz deli in New York it is cured with a dry cure and spices. The brine and or dry cure for pastrami also contains spices that are different than those used in a Corned beef brine such as pepper and a few others...... After curing pastrami is rubbed with a dry rub, smoked, then steamed. Corned beef is pulled right out of a brine and simply boiled till tender.