Tostadora vs. tostador
In spite of being quite similar, 'tostadora' and 'tostador', two Spanish words meaning 'toaster', have a subtle difference between them. Both of them refer to the device used to toast bread, but they are used slightly differently depending on the region of the Spanish-speaking world.
Tostadora
'Tostadora' is a feminine noun in Spanish that is universally used to mean a device for toasting bread.
Puse el pan en la tostadora.
(I put the bread in the toaster.)
La tostadora hace un ruido cuando el pan está listo.
(The toaster makes a noise when the bread is ready.)
Nuestra tostadora puede tostar dos rebanadas de pan al mismo tiempo.
(Our toaster can toast two slices of bread at the same time.)
Tostador
'Tostador' is a masculine noun that also refers to a device for toasting bread, but its usage tends to be more regional. In some parts of Latin America, it's more common to hear 'tostador' than 'tostadora'.
El tostador se rompió, así que no podemos hacer tostadas para el desayuno.
(The toaster broke, so we can't make toast for breakfast.)
¡Cuidado! El tostador está caliente.
(Careful! The toaster is hot.)
Tuve que comprar un nuevo tostador porque el viejo ya no funcionaba.
(I had to buy a new toaster because the old one was not working anymore.)
Summary
In conclusion, while 'tostadora' and 'tostador' both refer to the device for toasting bread in Spanish, 'tostadora' is universally understood, whereas 'tostador' can be more region-specific. Your choice between these two words may depend on the region where you are speaking or writing.