The Cultural Differences Between a US Firm and a European Firm in the US

Prior to joining a business school in Paris, I studied political sciences. There was no hint at the time that I would be heading into finance. Fast forward to today, you now work in a large European firm in the USA. But really you began your career at big American firms in London. What are the cultural differences like a US firm in Europe versus a European firm in America? It's an interesting question. Looking from the US, at times in Europe, maybe an easy concept, but it's a very complex reality.