IP and EP are a confusing. Originally SBS was going to use the term IP (Influence Points), for the currency that would be spent during Exposition to buy buildings and other items to help get the game world established. IP cost $5.00 per 50 IP
Then, SBS decided to have two types of IP, one that you could spend during Exposition (bonus IP, which cost $5.00 per 50 points), and one that showed how much you had contributed to the game financially or through getting the word out or otherwise contributing to the community (total IP). This was, as you might expect, extremely confusing.
Now, SBS has decided that the currency that will be used for Exposition will be called EP (Exposition Points), and IP will refer to your total contributions to the community through the money you have spent, the people you have recruited, etc. EP costs $5.00 per 50 points. IP will determine the order in which players join the Pre-Alpha experiences and Expositon, but will not allow you to purchase Buildings or other objects during Exposition. That always cost additional money.