Heba, you are going to have to provide us more information, such as full sentences and some context. All you have posted here are words.
Student or Learner
I want know Which one correct grammar:
They could both be correct. Give us a complete sentence and we can say which one should be used in that context.
You have been a member long enough to know that you must start every sentence with a capital letter and end every sentence with a single, appropriate punctuation mark, even a short sentence like "Thank you."
There was no need to capitalise "which" in your sentence.
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.