The words grievance, grievants sound the same but have different meanings and spellings. Why do grievance, grievants sound the same even though they are completely different words?
The answer is simple: grievance, grievants are homophones of the English language.
An actual or supposed circumstance regarded as just cause for complaint.
A complaint or protestation based on such a circumstance. See Synonyms at injustice.
Indignation or resentment stemming from a feeling of having been wronged.
Obsolete The act of inflicting hardship or harm.
Plural form of grievant.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition, 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").