The words prior, pryer sound the same but have different meanings and spellings. Why do prior, pryer sound the same even though they are completely different words?
The answer is simple: prior, pryer are homophones of the English language.
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.
<xref>Previously</xref>.
A person who <xref>pries</xref>.
See <internalXref urlencoded="prier">prier</internalXref>.
Definitions from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved., from Wiktionary, Creative Commons Attribution/Share-Alike License., from The Century Dictionary., from The American Heritage® Dictionary of the English Language, 5th Edition. 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").