How do the stay in Mina on the eighth and the standing on the ninth differ?

Book of Hajj: Sa’y between Safa and Marwa and the Day of Tarwiyah

• They are two names for the same site
• The first Mina stay occurs only after Arafat
• Sa’y is another name for Mina
• Recommended stay at Mina versus essential standing at Arafat