You can use oregano as a substitute for marjoram in recipes, but there are some key differences in their flavors. Marjoram has a milder, sweeter taste with a hint of floral and citrus notes, making it great for lighter dishes. Oregano, on the other hand, has a stronger, more robust flavor with earthy and slightly bitter tones. If you’re swapping oregano for marjoram, use a little less to avoid overpowering the dish.