Which is “better” (or at least less bad) for you?
The main difference is pastrami is smoked, corned beef is not. Both are essential the same thing, otherwise. I would call them equally good or bad for you. If you care about nitrates (I don’t), look for nitrate-free pastrami and corned beef. They will usually be a dull, brown color instead of the bright red you would typically expect (other than preservation and inhibiting the growth of botulism spores, nitrates and nitrites also preserve the red color in meat.)
Pastrami. Basic calories: 123(pastrami) vs 213(corned beef) for 3 oz. Pastrami is also lower in fat (4.8 vs 16.1) and lower in sodium(744 vs 964).
Depends on the corned beef. According to this 3 oz of corned beef is 120 calories.
They’re the same thing. One brand’s corned beef may be leaner and “healthier” than another brand’s pastrami and vice versa. If you get corned beef cut from the point then, yeah, it’s going to be leaner than pastrami cut from the flat. But a corned beef from the flat or the bottom round will be comparable to most pastramis (which tend to come from the flat.)
Missed edit: Actually, a lot of pastrami does come from the point/deckle, so you’ll just have to read the labels. You can’t generalize that one is better for you than the other in any meaningful way other than because of the presence of smoke.