"Our company" is a more formal and traditional expression, usually used in written language or formal occasions. It means "our company" ("we" means "us" or "mine" and "company" means "company").
"Fraud Section" is also a term that the company calls itself, but it is relatively rare. It may be more inclined to emphasize the shortcomings or problems of the company (such as "our company has some drawbacks"), but it is not necessarily true. This word is more common in everyday spoken or informal situations.
Therefore, if you want to describe your company in a formal or written context, we suggest using "our company". If you want to use it in everyday oral or informal situations, you can consider using the "fraud department". However, please note that the usage of "cheater" is not very common, and some people may misunderstand it.