Synonyms are those words whose pronunciation is same  but their spellings are different and their meanings are different - some of them are given here

(1) Coarse and course
(2) Cough and cuff
(3) Die and dye
(4) Male and mail
(5) Not, naught
(6) Sail and sale1
(7) Sight, site and cite
(8) Straight and strait
(9) Sun and son
(10) Tail and tale
(11) Week and weak