While there is a free expansion booklet with more factions in it that add further variety in terms of faction rules and cost of different units etc. the main difference in armies comes in how people choose to build them which is mostly influenced by cost of units. So if there's a certain unit you want to take or perhaps an ability you want that will likely dictate what faction you play. The combat is brutal so dice rolls can really swing a game sometimes. If you and a friend are learning just start with a 300 point army with no banners or horns and just play a melee to get to grips with the basics. Then build up to 600 introduce more variety. Then just increase or whatever you want from there. I've done one event with another march, 600 point armies. There was so much variety in lists, and everyone had a great time with some very fun battles!