Gözün aydın is used when something long expected happens. Like when a baby is born (to the parents or grandparents), someone returns from military service (to the family), someone returns home from a long journey etc. "Tebrik ederim" is very similar to the usage of "congatulations" (direct translation being i congratulate), like two people get married (to the couple), someone gets a degree or achieves something (to the achiever). Take care. :)

You can say ''gözün aydın'' to your close friends or your relatives.however, ''tebrik ederim'' is used for more official situations but not every time.it is up you :)

"Gözün aydın":We can say in English "I am happy for you" but in Turkish we use, for example:Somebody wants something and eventually it happens we can say to her/him "gözün aydın" or Somebody was far away and after he/she come back we say to his/her relative "gözün aydın" "Tebrik ederim":congratulation I hope it helps you.

both being used in almost in the same situation. tebrikler is a little more official usage you can also use it in a serious manner. "gözün aydın" is being used mostly among sincere people and mostly smiling manner when a good news being announced.

going to say, "Gözün Aydın" from .... From now on, you are very happy. Because, you have got .... or You have succeeded. going to say, "Tebrik ederim" is mean "Congratulations".