Drupal does things differently.
Instead of offering a packaged business directory you’ll build the functionality yourself piece by piece. Similar to how you build something using Lego blocks.
Building the functionality yourself is favorable because you get exactly what you want; nothing more, nothing less. It means you can implement custom business requirements much easier.
Building things from scratch means you have to understand the fundamental parts of Drupal. You’ll need to know how content is stored, rendered and displayed in lists or blocks.
If you don’t have this basic understanding you’ll hit a roadblock very quickly.