Apple has introduced a very subtle design change to the M4 MacBook Air that makes it easily identifiable next to M3 and M2 models.As iCulture.nl points out, theres a single identifying design choice for the M4 MacBook Air that is easy to spot but isnt immediately obvious. It comes down to the volume keys on the built-in keyboard. M2 and M3 MacBook Air mute keys use a plain speaker outline for the mute key. The M4 MacBook Air instead uses a speaker outline with a diagonal line through it for mute.The previous mute key icon made sense when compared to the volume down and volume up keys, but the new mute key icon is understandable without the comparison to the other volume key icons. It also matches the icon that Apple uses in software, and Apple is using the same mute key icon on the new Magic Keyboard for M3 iPad Air.The bigger design change, of course, is replacing space gray with a new sky blue color thats exclusive to the M4 MacBook Air for now. Best Apple accessoriesFollow Zac Hall on X, and listen to Runtime with co-host Sophia Tung on Apple Podcasts and YouTube.Add 9to5Mac to your Google News feed. FTC: We use income earning auto affiliate links. More.Youre reading 9to5Mac experts who break news about Apple and its surrounding ecosystem, day after day. Be sure to check out our homepage for all the latest news, and follow 9to5Mac on Twitter, Facebook, and LinkedIn to stay in the loop. Dont know where to start? Check out our exclusive stories, reviews, how-tos, and subscribe to our YouTube channel