Toasters have been a staple of almost all kitchens since the invention of the pop up toasters in 1825. Toast bread itself was eaten for a long time before that with most people skewering their bread on a long fork or sticks and toasting them over a fire.
Toasters became very popular because when eaten with sandwiches, they tasted much better than if plain bread was used. The second thing is that there was a subtle difference between putting in the filling and cheese and then toasting the bread – the cheese ran into the bread soaking it, and toasting the bread first and then putting it in.
Simple toasters also toasted bread much faster than the sandwich toasters or makers which meant that you could have more slices of bread in the same time. Often by the time you made yourself one sandwich the second batch of toast was ready.
The pop up toasters were the most common toasters, and are still preferred over sandwich makers throughout the world. As a machine it is very simple, you put in two or sometimes four slices of bread depending on the size of the toaster, and press down on a lever. This activates the heating element that toasts your bread within a couple of minutes and as soon as the bread is done, an automatic mechanism makes the bread pop up.
A variation of this theme is the toaster oven. This is nothing but a simple convection oven that has trays built in with heating elements in different levels so that you can toast your bread as a sandwich. Even though they are much smaller than conventional ovens, the toaster oven is good to make up to four sandwiches at the same time. It is therefore preferred by families who need more food at the same time. Of course you will not get the diagonal cut across the middle, but then if you were to get such a big sandwich toaster it would cost you two times what the toaster would.
Most pop up toasters cost around the $20 to $25 mark and you pay $10 or $15 more for the four slice toasters. Price wise there is not much of a difference between the sandwich toasters and the pop up ones. The sandwich toaster does not allow for big fillings because it will squeeze it all out when you shut it, while the toaster does not give you the option of getting a sealed sandwich and it is basically a preference for one or the other that governs your choice.