Which vs What
One should remember that though which and what are interrogative pronouns, there is difference between which and what in their usage. Both, which and what, are two kinds of relative pronouns that are used in the English language with difference. The origin of what lies in the Old English word hwæt. In the same manner, the origin of which lies in the Old English word hwilc. Moreover, in the English language, there are a number of phrases that use the words which and what. Which is which, and what have you, what not and what is more are some examples for those phrases.
What does Which mean?
Which can be used with nouns to ask questions as in the following sentences.
Which book has impressed you the most?
Which stamp do you want?
In the first sentence , you can see that the relative pronoun which is used with the noun book and, in the second sentence, you will find that the relative pronoun which is used with the noun stamp to ask questions.
Which is generally used in cases wherein there is a limited choice. Observe the following sentence.
Which color would you like? Green, blue or yellow?
In the above sentence, you can see that the choice given to the person is limited and hence the word that is used.
Which can be used as a determiner too. In fact, it is often used with a noun in a relative clause as in the sentence given below.
He may be late in which case we have to wait for him.
What does What mean?
What can be used with nouns to ask a question as in the examples given below.
What game do you want to play now?
What musicians do you admire?
In the first sentence, you can see the relative pronoun what is used with the noun game and the in the second sentence, you can see that the relative pronoun which is used with the noun musicians to ask questions.
Moreover, what is used when the choice is bigger. Look at the example given below.
What book is your choice?
In the above sentence, by the use of the word what you can find that the choice offered is certainly bigger.
What is the difference between Which and What?
• Which is often used with a noun in a relative clause.
• What and which can both be used with nouns to ask questions. In other words, both what and which are used as interrogative pronouns. This is one of the main purposes of the usage of the relative pronouns which and what.
• Which is generally used in cases wherein there is a limited choice. On the other hand, what is used when the choice is bigger. This is one of the main differences between the usages of what and which.
• It is important to know that what and which can be used as pronouns without nouns for that matter as in the sentences ‘which is better?’ and ‘what is more beautiful between the two? In both the sentences, you can see that the noun is not used but is simply substituted by the use of the words which and what respectively.