I am trying to understand the difference between building an app and simply making API calls from a database or server. I have a client with a store and the current requirements are to be able to get data from the store like sales and put items into the store. Basically mundane API work. I'm familiar with obtaining creds for doing these things and managing OAuth2.
What I don't quite get is where this fits in with the concept of an 'app'. My code would be running on my computer and simply pinging the API. From what I've picked up it seems like apps are generally concerned with interacting more substantially with the store. That is appealing and interesting but not what I need right now.
I'd appreciate a little guidance in terms of getting the concepts straight and links to the specific parts of the docs that talk about what I need to know.