Although there are some similarities, these two are different in most aspects such as model year, body structure, powertrain, horsepower, fuel economy, market segment, and ground shadow size. First of all, body structures are completely different. One is a Sedan and the other a Hatchback. The 2018 Clarity Plug-in Hybrid is also slightly larger than the 2021 Ioniq Electric. Also, the Clarity Plug-in Hybrid has a more powerful engine than the Ioniq Electric, and it gets 13 fewer miles on a gallon of fuel. Among similarities are the starting price and maximum occupancy.