The characters on his screen are made up of codes. Seven bits are all that are needed for each character. To keep things simple, computers usually add one more bit to that code to make a byte. So that's where the confusion comes in. Characters and bytes are each made up of eight bits, but that's all they have in common.
Characters are what show up on the screen, but bytes are what the computer works with.
Sometimes, of course, characters are what show up at your door trying to sell you something, but that's, ahem, a bit different, if you know what I mean.