If you’re a sole proprietorship or general partnership, you’ll need to file a DBA if you want your company to operate under a name that’s not your full, legal name, or your partner’s name. That’s because sole props and GPs are unincorporated, and they don’t need to file entity formation papers, and a business entity name, with the state. (Though they do still need to acquire the necessary business licenses and permits.)
So, they and their business are one in the same entity—which means they and their business have the same name, too—unless they file a DBA.
I hope it helped you!