Standard HDD configs are a 2.5-in 5400rpm drive for the 21-in and a 3.5-in 7200rpm drive for the 27-in model.
If you upgrade to Fusion, Apple sticks a 128GB SSD blade into the slot waiting for it. The HDD and SSD are then 'fused' into one 1.128TB or 3.128TB drive by software.
The base 21-in model doesn't have the slot for an SSD so can't be upgraded.
If you upgrade to Fusion, Apple sticks a 128GB SSD blade into the slot waiting for it. The HDD and SSD are then 'fused' into one 1.128TB or 3.128TB drive by software.
The base 21-in model doesn't have the slot for an SSD so can't be upgraded.