Apps are ways of connecting apps into your portal (using embedding or external linking) so that your clients can access everything they need in one place.
Manual Apps (formerly Local Extensions)
A Manual App is one that requires manual setup for each client, group of clients, or company. For example, if you are sharing a project status dashboard from Airtable, you will probably want to use a Manual App because each client would have their own project status dashboard.
Automatic Apps (formerly Global Extensions)
An Automatic App is visible to all of your clients and can be set up in a single step. For example, if you want all your clients to be able to schedule a call with you using Calendly, you will probably want to use an Automatic App.