With the sheer number of books and publications that come out of the United States, you’d be forgiven for thinking that the difference between writing American and British English simply boils down to minding your z’s and s’s.
While the Brits have generally accepted the use of “organization”, “realize”, etc., the same can’t be said for people on the other side of the pond, who may think you don't know how to spell if your document contains words like ‘organisation’ or ‘behaviour’. However, the difference goes much deeper and, when translating a document into English, it is essential that a) the translator be told which variant of the language should be used and b) that they know the differences.
For instance, bonnet is to hood, as petrol is to gas. And you wouldn’t tell an American that you have a flat, unless you’re expecting them to help you change your tyre (or rather, tire).
Similarly, in America you wouldn’t draw up Articles of Association for your business. Instead you’d need Bylaws and, when filing your financial statements with the IRS, your Profit and Loss Account becomes an Income Statement.
But it’s not only spelling and vocabulary that distinguishes these two variants. Grammar and punctuation also differ. For example, while Mr Smith’s company in the UK aims at achieving success, Mr. Doe’s American company aims to achieve that same success. And don't forget about date formats!
In Europe, and at least until the UK leaves the EU, British English is the official variant and, by default, is used in translations, although many businesses prefer to use the US variant to conform to popular usage. Either way, consistency is key and whichever variant you choose should be used throughout the document – that means spelling, grammar, punctuation and vocabulary.
Ultimately, know your target audience and adapt accordingly.