A business school will give you a more rounded business education. You’ll (likely) study things like Econ, Finance, Marketing, Operations, Accounting, Org Behavior, IT Mgmt, Business Law, and International Business. These are things that would help you start your own business or manage someone else’s. There is a lot of breadth to a BBA.
As has been stated, Econ is a liberal art – there is less real-world prep, but you’ll be able to use the lessons to make informed decisions. But unless the school offers electives in Finance, Acctg, Mktg, etc., you won’t get the same breadth. You’ll just know Econ extremely well.