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.
One who pries, especially a person who is unduly interested in the affairs of others.
One who pries; one who inquires narrowly; one who searches or scrutinizes. Also spelled <internalXref urlencoded="pryer">pryer</internalXref>.
One who pries; one who inquires narrowly and searches, or is inquisitive.
A person who <xref>pries</xref>.
Preceding, as in the order of time, of thought, of origin, of dignity, or of importance; in <em>law</em>, senior in point of time: as, a <em>prior</em> and a junior incumbrance.
Previous: used adverbially, followed by <em>to</em>, like <internalXref urlencoded="previous">previous</internalXref>. See <internalXref urlencoded="previous">previous</internalXref>, a.
A superior officer; a superior.
Formerly, in Italy, a chief magistrate, as in the medieval republic of Florence.
Definitions from The American Heritage® Dictionary of the English Language, 5th Edition., from The Century Dictionary., from the GNU version of the Collaborative International Dictionary of English., from Wiktionary, Creative Commons Attribution/Share-Alike License. and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").