The words tare, tear sound the same but have different meanings and spellings. Why do tare, tear sound the same even though they are completely different words?
The answer is simple: tare, tear are homophones of the English language.
Any of various weedy plants of the genus Vicia, especially the common vetch.
Any of several weedy plants that grow in grain fields.
An unwelcome or objectionable element.
The weight of a container or wrapper that is deducted from the gross weight to obtain net weight.
To pull apart or into pieces by force; rend.
To make (an opening) by ripping: tore a hole in my stocking.
To lacerate (the skin, for example).
To separate forcefully; wrench: tore the wrappings off the present.
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.
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").