The words prier, prior sound the same but have different meanings and spellings. Why do prier, prior sound the same even though they are completely different words?
The answer is simple: prier, prior are homophones of the English language.
A person who <xref>pries</xref>.
One who pries; one who inquires narrowly and searches, or is inquisitive.
One who pries; one who inquires narrowly; one who searches or scrutinizes. Also spelled <internalXref urlencoded="pryer">pryer</internalXref>.
One who pries, especially a person who is unduly interested in the affairs of others.
the head of a religious order; in an abbey the prior is next below the abbot
earlier in time
A high-ranking member of a <xref>monastery</xref>, usually lower in rank than an abbot.
Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License., from the GNU version of the Collaborative International Dictionary of English., from The Century Dictionary., from The American Heritage® Dictionary of the English Language, 5th Edition., from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved. and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.