Why are there wavy red lines under aluminium? What the heck does spoilt mean? Why should there suddenly be a hyphen between an adverb and a verb? Why can’t people decide if team is plural or singular?
Yes, there are two types of English (actually, there are more, but British and American are the two pertinent ones). Grammar rules, punctuation rules, spelling and word usage differ slightly between countries. So, which English is correct? They’re all correct. HOWEVER… readers may have a preference towards one or another, which means the writer must make a decision.
Location may help you make the obvious choice; if you are writing for American readers you should use American English, and if you are writing for British readers you should use British English. Those who assign or commission the writing may have a preference; if you are not sure, ask. If you are completely unsure of your audience, then just be consistent in your usage; don’t switch back and forth between American and British spellings, etc.
If you have learned to write in a society where both types of English are acceptable, you may not be able to easily differentiate one from the other. Just about any dictionary will help identify the spelling (the abbreviations being Br. for British, and Am. for American). Specific grammar rules can be found with a simple search on the internet (About.com has an interesting article which covers many topics). Clear punctuation is required in both types of English, but you can avoid cross-cultural errors by not using hyphens or semi-colons.
Sentenceworks is formulated to work with American English. American English is generally accepted in most places, and is a safe bet if there is any doubt as to which form would be best understood. However, British English can lend a more formal tone, which may be advantageous in certain situations.
Which is your favourite/favorite English?