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The main differences between American and UK English (so much more than colour/color)

Firstly, to make it clear, I am English and added to that I am a part-time English teacher. I am very much part of the UK English world, so when I started proofreading professionally and got my first American clients I can freely admit, I was not prepared.

I was lucky to have some very kind and patient clients as well as a lot of support from my US based LinkedIn connections as I was not fully prepared for just how many differences there are.

In the UK we are exposed to American English through film and TV as well as the internet but I hadn't ever really considered how many differences there actually are. The one that really threw me was that US American don't use practice - I remember asking the incredibly English Teacher question - "How on earth do you differentiate between a verb and noun?!"

So, without further ado, let's dive into what else I found!


One of the most noticeable differences between American and UK English is spelling. While we both use the same alphabet, we differ in the way we spell certain words.

For example, in UK English, words such as colour and flavour are spelt with "u". However, in American English, these words are spelt without "u", as color and flavor. Other spelling differences include the use of "s" instead of "z" in words such as realise (UK) and realize (US), and the use of double "l" instead of a single "l" in words like travelled (UK) and traveled (US). It is very easy to fall into your own pattern (for me especially the L thing).

Medical Terms

I mainly proofread medico-legal reports and boy have a I seen a lot of American spelling of medical terms in English reports.

Some common examples are:

  • edema/oedema

  • anemia/anaemia

  • hematology/haematology

  • tumor/tumour

  • fetus/foetus

  • pediatric/paediatric

  • leukemia/leukaemia

  • ischemia/ischaemia

  • esophagus/oesophagus

This can be particularly tricky when the author is using a medical term they are not familiar with, a quick Google search isn't always reliable as many of the

websites that pop up first use American English as they are US based (think Mayo Clinic and PubMed)

For UK spelling of medical terms, I rely heavily on the good old NHS.


Another area where UK and US English differ is grammar. For example, in UK English, it is common to use the present perfect tense when describing past events. However, in American English, the simple past tense is often used. For instance, in UK English, you might say, "I have just finished my work", whereas in American English, you would say, "I just finished my work". This is a difference that won't always be picked up by simply switching your dictionary settings.


UK and US English also differ in terms of vocabulary. For example, in the UK, people often use the word "lorry", whereas in the US, the word "truck" is more commonly used. Similarly, in the UK, people often use the word "lift", whereas in the US, the word "elevator" is more commonly used.

I feel the exposure we have in the UK to US media helps with this enormously. However some vocabulary is very specific to context, for example my first job I worked in a deli, the American owner asked me to get her a skillet; I literally had no idea what she was on about, in England we call it a frying pan. If you are writing for a specific niche, and are not sure, ask.


Whilst punctuation rules are generally similar in both UK and US English, there are a few notable differences. For example, in UK English, it is common to use double quotation marks (" ") to enclose a quote, whereas in American English, single quotation marks (' ') are more commonly used. Additionally, in UK English, punctuation is placed inside of quotation marks, whereas in American English, punctuation is often placed outside quotation marks. Again this is very easy to miss. However, it is important to remember that with global business and word processing these conventions are constantly evolving. Taking the time to look it up and having a prompt sheet handy, will help you switch between codes.

If you're looking to get a piece of writing proof-read, it's important to specify which variant of English you're using to ensure that your proof-reader is able to catch any errors that may arise from using the wrong form.

Contact memo from either side of the pond for all your proofreading needs.


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