Both words can be correctly utilized in a properly arranged sentence.

Prior to the previous message, I had a simpler plan.

The previous Prior was taller.

Prior to 1810, the Royal Mint was located at the Tower of London.

My Space!

Prior to using an AED you should confirm the absence of a pulse.

Prior to the Civil Rights movement, there was general inequality which was socially or lawfully enacted. Prior to this movement was laws that denied equality regarding Blacks given the same rights as Whites.