GameMaker, RPG Maker and Construct 2 are all game design and creation programs that enable virtually anyone to make his own computer video game. Each of these applications is designed for a specific market, and each caters to the desires and needs of that market in unique ways.
GameMaker is available for both Windows and Mac OS X, and it is a program used for making two dimensional games on both a simple and complex scale. Visual design elements are available in GameMaker, as well as a robust programming language, so that both beginners and experts are able to create games as quickly and easily as possible.
RPG Maker, as the name implies, is a game creation program that focuses only on making role-playing games. It is available on the Windows operating system and is designed for beginners. It has a simple point-and-click interface used for creating intricately designed top-down two-dimensional RPGs.
Construct 2 is similar to GameMaker, although it is only available for Windows. Like GameMaker, it enables the creation of two-dimensional games, but it focuses more on point-and-click interfaces and offers less access to the intricate programming methods that GameMaker features. This program, like RPG Maker, is targeted towards beginners, and more advanced game designers won't have the ability to make complex games with the program.