US English VS UK English

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Again this is in reference to academic wriitng projects. There are some that requires US English which I really have no problem about however, there are some good topics that I know I can write about however they are requiring UK English for that paper. Sorry if this could make me sound stupid to some but I really need to know if there is a significant difference between US and UK English when it comes to academic writing? I can understand some terms such as a guy or a man in US english is a chap or a bloke in UK english but is this formal english used for academic papers for instance? Thanks again in advance for your help.