The words beetle, betel sound the same but have different meanings and spellings. Why do beetle, betel sound the same even though they are completely different words?
The answer is simple: beetle, betel are homophones of the English language.
Any of numerous insects of the order Coleoptera, having biting mouthparts and forewings modified to form horny coverings that protect the underlying pair of membranous hind wings when at rest.
An insect resembling a member of the order Coleoptera.
To make one's way or move like a beetle: "Chambermaids . . . beetled from bedroom to bedroom loaded with . . . champagne” ( Vanity Fair).
Jutting; overhanging: beetle brows.
An evergreen Indo-Malayan climbing or trailing shrub (Piper betle), having usually ovate leaves used to wrap betel nuts.
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.