Montón vs. pila
In the Spanish language, 'montón' and 'pila' are commonly used to refer to a 'heap', 'pile', or 'stack' of objects placed on top of each other. The two words are often used interchangeably, but they do have some subtle differences based on context and regional usage.
Montón
'Montón' is typically used to refer to an informal or disorderly pile or large quantity of things.
Tengo un montón de tarea que hacer.
(I've got a heap of homework to do.)
Hay un montón de basura en la calle.
(There's a heap of trash on the street.)
Pila
'Pila' refers to a more orderly stack or pile of objects. It can also be used metaphorically to imply a large amount or a lot of something.
Hay una pila de libros en la mesa.
(There's a stack of books on the table.)
Tengo una pila de cosas que hacer hoy.
(I have loads of things to do today.)
Summary
While both 'montón' and 'pila' can be used interchangeably in many contexts to describe a heap, pile or large quantity, 'monton' is generally used to describe an informal or disorderly pile, while 'pila' usually refers to an orderly stack. Regional variations and context often dictate the preference for one term over the other.