The words succor, sucker sound the same but have different meanings and spellings. Why do succor, sucker sound the same even though they are completely different words?
The answer is simple: succor, sucker are homophones of the English language.
Assistance in time of distress; relief.
One that affords assistance or relief.
To give assistance to in time of want, difficulty, or distress. See Synonyms at help.
One that sucks, especially an unweaned domestic animal.
Informal One who is easily deceived; a dupe.
Informal One that is indiscriminately attracted to something specified: "The nation's capital is a sucker for a symbolic gesture” ( Jonathan Alter).
Slang An unspecified thing. Used as a generalized term of reference, often as an intensive: "our goal of getting that sucker on the air before old age took the both of us” ( Linda Ellerbee).
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.