When comparing accross countries, I wouldn’t be surprised if different countries had different methodologies for calculating GDP. The differences don’t have to be obvious at the first sight. For example, both countries may agree that GDP = X + Y + Z, but there may be a huge difference in how exactly they calculate X, Y, and Z. Also, gray economy may or may not be included, and may be estimated incorrectly.
(Sometimes such changes are done for obvious political reasons, for example in my country a government once reduced unemployment by simply changing the definition of how unemployment is calculated. Another example of how the same word can correspond to different things is how countries calculate tourism: in some countries a “tourist” is any foreiger who comes for a non-work visit, in other countries only those who stay at a hotel are counted.)
When comparing accross countries, I wouldn’t be surprised if different countries had different methodologies for calculating GDP. The differences don’t have to be obvious at the first sight. For example, both countries may agree that GDP = X + Y + Z, but there may be a huge difference in how exactly they calculate X, Y, and Z. Also, gray economy may or may not be included, and may be estimated incorrectly.
(Sometimes such changes are done for obvious political reasons, for example in my country a government once reduced unemployment by simply changing the definition of how unemployment is calculated. Another example of how the same word can correspond to different things is how countries calculate tourism: in some countries a “tourist” is any foreiger who comes for a non-work visit, in other countries only those who stay at a hotel are counted.)