Tha is a difficult question to answer. The ANZSCO Code for Accountant is 221111 and for Internal Auditor is 221214. According to Schedule 6D you get 5 points for a professional year if the professional year is for your nominated occupation or for a closely related occupation. DHA policy is that an occupation is closely related if the first 4 digits of the ANZSCO Code are the same. As you can see they are not the same in this case.
There is some wriggle room though. When you read the policy carefully it does make allowances in certain cases. I think you better seek advice from an expert on this one.