1. Expenditure adjustment: the planned expenditure amount during budget preparation may need to be adjusted due to changes in actual conditions. There may be some extra expenses or emergency expenses, which may cause the actual expenses to exceed or fall below the budgeted amount.

2. Allocation of funds: In the process of budget implementation, funds can be reallocated according to actual needs and priorities. Some projects or activities may be cancelled or postponed, while others may require additional input. Therefore, the budget amount may be different.

3. Economical measures: In the process of budget implementation, some economical measures can be taken to reduce expenditure. This may include cost control measures in procurement, operation or other aspects, which eventually leads to the actual expenditure being lower than the budgeted amount.

4. Operational errors or management problems: In some cases, the inconsistency between the actual expenditure and the budgeted amount may be caused by operational errors or management problems. This may require further review and improvement of management and control mechanisms.