In August 2020, however, only the 27-inch iMac received an update. That way, internals between both options are mostly the same. It's time to take a look at the most current iMacs on the market! Break it down nowĮach year, Apple usually releases new iMacs at the same time. It's because of this that we're recommending one model over the other. Much of this is because one was just refreshed, and the other has not. Internally, they are different beasts entirely. Display size isn't the only thing different between the 27-inch iMac 5K (2020) and 21.5-inch iMac 4K (2019).