Maleta vs. valija

The words 'maleta' and 'valija' both translate to 'suitcase' in English, but are used differently depending on geographical location.

Maleta

'Maleta' is the most universally accepted term for 'suitcase' in Spanish-speaking countries.
Voy a hacer mi maleta para el viaje.
(I am going to pack my suitcase for the trip.)
¿Dónde está mi maleta?
(Where is my suitcase?)
¿Podrías traer la maleta al coche?
(Could you bring the suitcase to the car?)

Valija

'Valija' is typically used in Argentina and Uruguay and less commonly used in some other Latin American countries, to mean 'suitcase'. However, it is less common and sometimes might refer to smaller types of luggage.
¿Has visto mi valija?
(Have you seen my suitcase?)
Voy a comprar una nueva valija para mi próximo viaje.
(I am going to buy a new suitcase for my next trip.)
Guardé toda mi ropa en la valija.
(I packed all my clothes in the suitcase.)

Summary

'Maleta' and 'valija' are both used to refer to the same English word, 'suitcase', but the usage of each term varies by region. Usage of 'valija' can sometimes also indicate a smaller type of luggage.