1st round - HR Screener with in depth questions. Very polite.
2nd round - Controller - Very informal I asked all the questions.
3rd round - CFO - He had not reviewed my resume so I hade to go through my entire resume for him. He was extremely polite and thorough. Pretty formal.
My interview with the controller, she did not ask me any quest. Just let me ask all of the questions. She referred to her staff as lazy, but in reality - she seems pretty lazy by not wanting to be bothered with her staff.
After the final interview, the head of HR sent me a couple of emails stating that they were still interested but had not made a decision. I realized these emails were intended to keep me "warm" while they made offers to other candidates. Eventually they got around to me and I declined.