Brits call American chips, "crisps" when referring to the thin and crunchy bagged snack chips.
British people call American fries, which are the thick cut fried potatoes, "chips".
This can lead to confusion, like "fish and chips" uses the UK "chips" for what the Americans call fries.
The American "chips" which are the bagged snacks are called crisps by the Brits, like the bag of lay's potato chips would be called a bag of crisps by the Brits.
The American "fries" which are the thick cut fried potatoes are called "chips" by the Brits like in fish and chips.
Basically chips in the UK are the equivalent of "French fries" in the USA.
Although the term French Fries are also associated with the thin things called chips.
So it can be confusing if you're from America and go to the UK and want chips or fries.
You have to remember to ask for the correct thing or you would likely get the wrong snack or food product.