Differences between US and UK English that language professionals should know

The different dialects of English present an interesting challenge for professionals working in language services.

On one hand, the differences between these dialects tend to be fairly minute — speakers of most dialects of English can generally understand each other without any major miscommunication. Spelling the word “localization” with an “s” instead of a “z,” for example, is not likely to confuse any US-based native speakers of English, who typically use the “z”-spelling. Likewise, spelling “color” in the American fashion (as opposed to the UK’s “colour”), is equally unlikely to cause any confusion for UK-based English speakers.

On the other hand, tailoring a product to adequately reflect the spelling and vocabulary of a specific locale is an important aspect of attracting an audience within your target demographic. Especially in the age of search engine optimization (SEO), it’s important to use the standard spellings and vocabulary that your target audience uses.

Given that there are many dialects of English (after all, any language with more than 1 billion speakers is bound to have some variation), it would be impossible to identify the distinctive quirks of every single one. Instead, we’ve selected three key areas in which US and UK English — two particularly prominent dialects of the language — differ. These distinctions should serve as a launching point for further, more specialized research when working on a translation or localization project that needs to be catered to a specific English-speaking audience.


One of the most obvious differences between these two dialects is spelling.

For the most part UK and US speakers of English use the same spellings for the same words, but there are quite a few differences that are particularly important to keep in mind for SEO purposes. If you’re looking to attract customers or an audience that’s based in the US, they may not be able to find your company as easily as you probably want if you’re using British spellings of words, like “organisation,” for example.

Here are just a few common spelling differences to keep in mind:

  • “-ize” vs. “-ise” — The suffix “-ize” is commonly appended to English words to turn an adjective into a verb (i.e., the adjective “local” becomes the verb “localize”). In the UK, this suffix is spelled “-ise.” When other suffixes are added onto the words (i.e., “localise” to “localisation”), the spelling difference remains, even though both dialects pronounce the “s” or “z” symbol here as the same sound. Here are a few examples:
    • “localize” vs. “localise”
    • “organize” vs. “organise”
    • “realize” vs. “realise”
    • “generalization” vs. “generalisation”
  • “-or” vs. “-our” — In most cases, UK English speakers will end words with “-our” in cases where US English speakers use “-or.” There are a handful of exceptions to this rule (for example, “author” and “editor” are spelled the same in both dialects), so it’s always best to double check in a dictionary that reflects the regional dialect (Merriam-Webster is a good option for US English while the Oxford English Dictionary is a good option for UK English). A few examples are:
    • “color” vs. “colour”
    • “favor” vs. “favour”
    • “humor” vs. “humour”
    • “labor” vs. “labour”
  • “-ense” vs. “-ence” — Words like “defense” and “offense” in US English are spelled with an “s” in place of the “c” in UK equivalents. When certain suffixes are added to these words in UK English, the “c” might revert to an “s,” making it indistinguishable from the US spelling — this doesn’t always happen though. British “defence” becomes “defensive” when adding the “-ive” suffix, but the “c” remains in the UK spelling of “defenceless.” While there aren’t too many words that have this distinction, the words it does affect are quite common — here are some more examples:
    • “license” vs. “licence”
    • “pretense” vs. “pretence”


Another obvious difference between these two English dialects is the vocabulary they use. Most native English speakers are aware of particularly common or amusing differences — take, for example, the difference between “chips” in the US and the UK. In the US, this refers to a class of snacks that UK English speakers will know as “crisps” — typically some sort of thinly sliced or pressed carbohydrate (i.e., potatoes or corn) that’s been fried or baked. In the UK, “chips” are thick-cut and deep-fried potatoes — what we’d call “French fries” (or more specifically, “steak fries”) in most parts of the US.

Once again, speakers from both the UK and the US can understand each other fairly easily — these vocabulary differences aren’t likely to cause any huge error in communication. Still, it’s good practice to use vocabulary that matches that of the targeted locale. Here are just a few instances of words whose meanings differ depending on whether you speak US or UK English.

  • “holiday” — In the US, this word really only refers to special days meant for celebration — think Christmas or Memorial Day. On the other hand, UK speakers might also use this word to refer to what US residents call a “vacation” — time off from work or school.
  • “petrol” — This is a common word used throughout the UK to refer to the petroleum-derived fuel used for driving an automobile. North Americans rarely, if ever, use this word — instead, they use the words “gasoline” or “gas” in its place.
  • “pants” — Though it’s a fairly innocuous term in the US, if you were to walk around town wearing what UK residents call “pants,” you’d look a bit out of place. That’s because the word “pants” in the UK refers to underwear — not the outerwear US dwellers call “pants” Instead, UK residents use the word “trousers.”

Of course, the vocabulary differences are far too many to list in one article. Since these differences can be found throughout all sorts of different situations, it’s important to have an understanding of the ones that are most relevant to your field.


Perhaps the easiest difference between the two dialects to consistently target is their measurements.

The United States is notorious for its adherence to the Imperial system of measurement. This means that US speakers of English will measure things in feet, pounds, and ounces, among other units of measurement. This is a relic from bygone days when the UK and its colonies also used the Imperial system — well before the International System of Units (what we colloquially refer to as the metric system) was developed. 

Nowadays, the UK — as most other countries throughout the world — uses the standard metric system. When working on a project in US English, you’ll want to be careful to convert measurements to the Imperial system so as to avoid confusing your stateside consumers.


Andrew Warner
Andrew Warner is a writer from Sacramento. He received his B.A. in linguistics and English from UCLA and is currently working toward an M.A. in applied linguistics at Columbia University. His writing has been published in Language Magazine, Sactown Magazine, and The Takeout.

Weekly Digest

Subscribe to stay updated