Phone numbers in different countries are formatted differently. The most common format used in the US is the 10-digit format, where the first three digits are the area code, followed by the seven-digit local number. For example, the format for a US phone number could look like this: (123) 456-7890.
In contrast, many other countries have adopted the international format for phone numbers, which includes the country code followed by the local number. The country code is a unique number that is used to identify the country of origin for the phone number, and is usually one to three digits long. For example, the format for a UK phone number could look like this: +44 20 1234 5678.
In summary, US phone numbers are formatted as 10 digits, while international phone numbers consist of a country code followed by the local number, and the total number of digits can vary from country to country.