Maingano is a specific type/ described species with rather consistent horitzontal stripes, body shape, and they keep a blue/ black color but they can vary from lighter to darker when adults.
Electric Blue Johanni is a mass market fish that seems to be a hybrid much of the time, or poorly bred, but sometimes Maingano have been sold as Electric Blue. Electric Blue Johanni tend to be more variable and inconsistent, and adults are often not very attractive.
They may regard themselves as conspecific, and will crossbreed, and males may fight like they are the same. If you can get good Maingano, just get the Maingano.