What is the difference between usury and riba

The Permissible Transactions and the Transactions of Riba (Interest and Usury)
The Permissible Transactions and the Transactions of Riba (Interest and Usury)

The Permissible Transactions and the Transactions of Riba (Interest and Usury) His Eminence, Ash-Shaykh 'Abdul-'Aziz bi...