Account Assignment-Asset development

Here we are developing assets inside the company.

I know that for booking expenses, in PR, we can give an account assignment as Internal Order or an Asset. I am unable to understand what is the difference in using Internal order or an asset (AuC) directly in the account assignment for the asset development ?

If we use internal order, we have to settle it to the Asset. But if we use Asset, we need not do the settlement process. Then what is the advantage of using either of these two account assignment ?