See Business law deals mainly with the legalities for an organization's foundation. But corporate law emphasis on the operations, activities, and validity of an organization.

In simple terms you can think of it like the Corporate lawyers makes the contract and the work of review is done by the Business Lawyers.

So the corporate law mainly focuses with the legalities of the company itself and creation of its own policies whereas the Business law deals with the overall law system starting with the local law to the constitutional law.

This is a very rough difference but I hope it helps. All the very best for your future endeavors!