When creating a subscription using the PayPal Subscriptions API, the status value in the HTTP response can be APPROVED but it can also be ACTIVE.
How are these different?
An ACTIVE Subscription is, well: active. It will do everything you expect it to do over time.
An APPROVED Subscription was recently approved (consented to) by a payer, nothing more. It won't do anything unless activated.
What happens after a Subscription is approved? The default user_action is SUBSCRIBE_NOW, which activates the subscription immediately and automatically on approval. However, you can change that by setting to CONTINUE instead, and show a final review step after the return, before activating with a separate API call.