The skills interview is with 3 people, they ask a few questions about your work history, approach to problems and situations and give you a case to work on on the spot. For me it was how I would approach 2 client problems with research and how I would work with the various teams. They also ask a few questions about my management style and what I am looking for in the role.
For the culture interview, it's 3 people and they take turns asking questions about how you would generally handle conflict, what kind of environment you prefer, what kind of teams you prefer, how you choose to deal with overwhelmed work etc. Then they give you 12 traits (empathetic, strategic, organized, delegate etc.) to choose 3 from and explain why you chose those.