What's the Difference Between Portobello and Cremini Mushrooms?

Astute grocery shoppers may have surmised this already, but it's a pretty neat finding nonetheless: cremini and portobello mushrooms are the same species of fungi at different stages of maturity. (This is why cremini mushrooms are sometimes labelled as baby bella mushrooms.) Larger, meatier portobello mushrooms are cremini mushrooms that have been allowed to grow for an additional five to six days. During this extended growth, the mushrooms become drier, denser, and more flavorful; additionally the gills open up, providing more flavor.

Trivia aside, it's worth noting that the two can be used interchangably to some extent. While any recipe that relies on the size of either mushroom should be made with the variety that's called for (think stuffed mushrooms and portobello burgers), if the mushroom will be chopped, diced, or otherwise broken down, either will typically suffice.