The BI department is inside the IT department or GBS - at least when I was there, but I remember they were changing that when I left and moving that to the strategy part of the company -, so in my case, I applied to an IT position and then said that I was more interested in BI. So the possibilities of what you could be doing are huge. More core IT people will be working with internal systems, infrastructures, SAP, etc. while if you are on the BI team you will be more focused towards the business and the customers. Usually, most of the BI members are something like Customer Analyst, they work with one specific customer and sales or marketing team to process, analyze data and visualize it for the team in order to see how the business is going, build metrics and those kinds of things.