Are you checking broad or exact match phrases?
car insurance and insurance car are equal because these are broad match types
[car insurance] and [insurance car] are very different because these are exact match types
Numbers are rounded in order to make them easier to read and manage. 195,000 is easier to read than 194,793 and that slight difference doesn't really matter. Same with 590 and 587.
The "reliable source" you linked is a forum where an unknown person posted a message. That is not something I would rely on. Read more about SERP CTR and check your website's data and you will see that the numbers are roughly correct.