The features you have end up being the same (more on that below). The differences shown below are only related to what prerequisites you already have in order to determine pricing.
Pricing for the E3/E4 plans is shown in the next screen shot. The importance of E3/E4 is that they come with Office 2013 Professional Plus and SharePoint Online (SPO) Plan 2 – both of which are important prerequisites for Power BI features and functionality.
Let’s say you are an E3 subscriber at $20/month. Add the $20/month special offer price for Power BI and it’s a total of $40/month per user. That’s much better pricing than the $52 shown in the far right hand column of the pricing chart. Hmmm…sounds like a price break to entice more customers to the Enterprise Office 365 plans.
Good tip! 🙂