What's the difference between a Meritage and a red blend?

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.
Dear Dr. Vinny,
I really enjoy red blends. What's the difference between a Meritage and a red blend?
—Jerry M., Tucson, Ariz.
Dear Jerry,
I’m with you! There’s something really satisfying about a great red blend. Red blends have been trendy lately because some of them are quite affordable and easy to drink—and there’s nothing wrong with that.
Meritage (rhymes with “heritage”) is a particular category of blended wine. To use the term, a winery has to be a member of the Meritage Association, and the wine has to be blended entirely from Bordeaux grape varieties, with no more than 90 percent of any single grape.
Keep in mind that a Meritage can be a white wine if the blend is based on Sauvignon Blanc, Sémillon and Muscadelle, but most of the time I see red Meritages, which can include grape varieties like Cabernet Sauvignon, Merlot, Cabernet Franc, Malbec and Petit Verdot.
—Dr. Vinny