PRIVATE DISTRIBUTION is when your app is not publicly available on the app stores. You'll need to create an Apple Business Manager Account. Your app will be available to download from a QR code and landing page that you can give to clients.
PUBLIC DISTRIBUTION is when your app is on the Apple App Store and Google Play. You'll need to create Apple and Google Developer Accounts. The cost for these is about $150 annually and is not included in your annual fee to us.