Hi there, MrsTaxPro.
QuickBooks is for recording purposes and it's possible that there are expenses or payments made outside that were not recorded within QuickBooks.
The Payroll Expenses account tracks payroll items that are an expense to your company. These includes salaries, wages, bonuses, commissions, company contributions such as a company-paid health plan, and the company-paid portion of taxes like Social Security and Medicare.
On the other hand, the Payroll Detail report shows the pay checks you've created, including the amount, taxes, and deductions, and some items in the report is not included in calculating the payroll expense.
You can check out this articles that will give you more information on what is shown on our payroll reports.
Let me know if you need anything else. Take care!