The words emerge, immerge sound the same but have different meanings and spellings. Why do emerge, immerge sound the same even though they are completely different words?
The answer is simple: emerge, immerge are homophones of the English language.
To rise from or as if from immersion: Sea mammals must emerge periodically to breathe.
To come forth from obscurity: new leaders who may emerge.
To become evident: The truth emerged at the inquest.
To come into existence. See Synonyms at appear.
To submerge or disappear in or as if in a liquid.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.