The kerbs keeps growing. The oregano and marjoram have tangled up with each other and…fused. And, honestly, I just can’t tell the difference between them. They look exactly the same. I mean exactly. They smell pretty similar, too, just as kitten siblings smell alike–but perhaps not identical, not quite. The differences are so subtle, though, that half the time I wonder if I’m imagining it. The marjoram is, hmmn, milder maybe, gentler. The oregano has a slightly drier, harsher scent. Key words here: perhaps, maybe, slightly.
I suppose all this means is that we’ll have to start cooking different things and seeing how the two herbs shade those flavours. Or not.
Anyone got any suggestions for recipes that will bring out the difference?
Nicola Griffith 
Real Texas chili calls for wild marjoram instead of oregano. In fact, wild marjoram is often referred to as Mexican Oregano. I don't know if “tame” marjoram is any different.
I've come to prefer marjoram for anything calling for oregano, for the reasons you cited above: milder, gentler. It's one of my favorite things to smell. They're closely related (both genus oreganum), but I find the distinctions important when I cook.
I agree with Bridget, prefer to use marjoram. The base oils contained in the plants are the same but oregano has a slightly harsher, more wild flavour, it's also more vigorous.
It's just good to know I'm not crazy! Thank you.
I'm a huge marjoram fan, and absolutely agree with your “milder” analysis.
I believe that some Italian regions use oregano predominantly, and some use marjoram; now of course I can't find anything useful in my Italian cookbook!
Whoah! Welcome to the jungle!
I now have the sudden urge to grab a machete and start chopping in the search for ancient Mayan ruins.
http://www.cookthink.com/reference/62/Marjoram_vs_oregano
http://www.sallybernstein.com/food/columns/gilbert/oregano.htm
transceptor, maybe I'll get some little plastic models of temple ruins to stick in there…
Dianne, thanks for the links.
I think that is an excellent idea :D
I was reading a book about herbs many years ago (can't remember the title). The chef who wrote it said that all food tastes better with herbs, and you can dress food with any herb and it will taste good. However, many foods taste even better dressed with specific herbs. Carrots are sweet and gentle tasting with marjoram. To me, marjoram has a sweet and lemony taste. Oregano hits you square on your nose and cuts through the sweetness of tomatoes. Every herb shines with its partner vegetables. Nice!
Sharon, I use oregano in Bolognese sauce (along with bay leaves). I'm not a fan of tomatoes in general, but will use a little in sauces for pasta (I'm less sensitive to them if their skins are removed and the seeds strained out). Why? Haven't the faintest idea.