The details for Prime explicitly refer to it as Two Day Delivery, not shipping.
Prime Membership Benefits
Delivery benefits
FREE Two-Day Delivery: Millions of items delivered fast and free.
FREE One-Day Delivery: Available on more than 15 million items with no minimum purchase.
FREE Same-Day Delivery: Available, in select areas, on over 3 million items for qualifying orders that meet the minimum threshold of eligible items, in as fast as five hours.
The details for Prime explicitly refer to it as Two Day Delivery, not shipping.