Audit assistant can be an enterprise accountant or accounting supervisor in the future; Tax assistants can develop into financial supervisors or planners in the future. Both positions are likely to be CFO positions.
If you are in a small accounting firm, it is best to be an audit assistant, because small accounting firms are generally not exposed to more complicated tax practices, that is to say, it is only the calculation and audit of general taxes. From this perspective, audit assistants can also be exposed to such businesses (value-added tax and income tax). Only large accounting firms with fine division of labor can undertake complex business, such as tax planning within group companies, tax treatment of mergers and acquisitions and so on.
Personal advice, for reference only.