The adjectives prior and previous are both useful synonyms of earlier or past, and there is no substantive difference between them. Searching the web, we find people making all sorts of assertions about the difference between the words, but these reflect the writers’ own preferences rather than any objective examination of how the words are used. In real-world usage, prior and previous are usually interchangeable.
But prior to and previous to are wordy for before.
Examples
Before could replace the verbose prior to and previous to in these examples:
The city planned for last week’s blizzard three days prior to the storm hitting the area. [The Herald-News]
Previous to this legislation, there was no list and developers were either surprised when they got their bills or they were never billed. [quoted in Watertown Daily Times]
Prior to his stint as the team’s head coach, Shannon served as the Hurricanes’ defensive coordinator for six seasons. [Washington Post]
Previous to his announcement, the military announced on state television that its Supreme Council was in permanent session … [The Spectrum]
And these writers use prior and previous well:
Mayor Robert Dean Smith was arrested Wednesday on allegations he violated a probation from a previous drunken driving conviction. [KJRH.com]
The two have a prior relationship from their days with the New York Giants and will likely play a significant role in offensive game-planning. [Milwaukee Journal Sentinel]
Pawlenty, the previous governor of Minnesota, delivered a speech … [NPR]
In her prior position as San Francisco District Attorney, she was instrumental in securing legal protections for the lesbian, gay, bisexual, and transgender (LGBT) community … [Lez Get Real]
