In concept, a blazer with jeans is an endlessly-wearable marriage of tailoring and workwear; a high-low hero. Or the Boomer penchant for a one-size-too-big suit jacket with puddled dad jeans. Like peanut butter and jelly, gin and tonic, or Mick and Keith, blazers and jeans are just a legendary high-low handshake. The main thing to know is: a suit jacket does not a blazer make. A suit jacket is usually cut from smoother, finer wool, and often has flap pockets.