Steam has long been the pre-eminent games engine for consoles, but EA games made a clear attempt to supplant steam with their own gaming engine Origin. Most gamers would say now that both are essentials for any PC gamer, as both of them offer uniquely different things.
EA games is one of the largest gaming developer companies in the world, and all of their games are available solely on Origin for PC. This means that anybody who wants to play a game like FIFA, or Star Wars Battlefront, has to go to Origin. The downside to this gaming platform is that their internal online shop is a bit on the expensive side, so those who are operating on a budget should avoid it.
Steam is a lot more open, allowing users to play a wide assortment of game titles. They have an extensive list of free games available for users to play at no cost; more than enough game titles to keep you occupied. The platform has a number of the biggest game titles in the world on it, such as Battlefield, as well as a massive number of online games, such as Dota 2.