The Power User Subscription gives you the features listed in the article I linked to. Affinity doesn’t give you these, with the exception of segmented profit and loss which is included in Affinity.
There’s a more detailed list of features included with the Power User Subscription here. If you don’t have the subscription, you wouldn’t have these features (except, as I mentioned above, the segmented P&L report).
Affinity is a separate product to the power user subscription, so there’s no transfer needed. However, when an account is linked with Affinity, the power user subscription is optional. So once it expires, it’s optional if you renew it.
I hope that helps.