Who vs. Whom
Main DifferenceFirst of all, 'Who' is a subjective case for the subjective pronoun 'he', and is used as a relative pronoun in the middle of the sentence. 'Whom', although is also a relative pronoun, is an objective case of the pronoun 'he' and is also used as a relative pronoun in the middle of the sentence. Not only for the complex sentences, where both these words are used in the middle of the sentences to relate the other part of the sentence to make it one, these two pronouns are also used in the Interrogative sentences but at the beginning instead of in the middle of the sentence. 'Who' is used as the subject of the verb in the sentence e.g. 'Teacher punishes the student who came late', 'I played with the student who challenged me'. For interrogative sentence, 'Who broke the glass'? 'Who is there behind the wall?', 'Who fought with you last night'? On the other hand, 'Whom' when comes as a related pronoun in the middle, refers to Object, playing the role of its pronoun e.g. 'She returned the pen to the boy whom she borrowed earlier', 'She is the girl whom our teacher called diligent student'. For the interrogative sentence e.g. 'Whom did you hand over the letter?' 'Whom did she call for help'?

Difference Between Who and Whom
Who vs. Whom
Basically, 'Who' is used as a Subject in a sentence; 'Whom', is used at the opposite side of 'Who' as Object in a sentence
Who vs. Whom
Both these words are pronouns but with the difference that one is used as a Subject and other is used as an Object in a sentence
Who vs. Whom
The pronoun 'Who' is placed in the middle of the sentence to provide detail about the subject; 'Whom', also provides detail, but unlike 'who' for the Object in a sentence
Who vs. Whom
'Whom' can never be used as a Subject; 'Who' is always used as a Subject and can never come as Object
Whopronoun
(interrogative) What person or people; which person or people; asks for the identity of someone. (used in a direct or indirect question)
Who is that? (direct question)I don't know who it is. (indirect question)Whompronoun
What person or people; which person or people, as the object of a verb.
Whom did you ask?Whopronoun
(interrogative) What is one's position; asks whether someone deserves to say or do something.
I don't like what you did, but who am I to criticize you? I've done worse.Whompronoun
What person or people; which person or people, as the object of a preposition.
To whom are you referring?With whom were you talking?Whopronoun
(relative) The person or people that.
It was a nice man who helped us.Whompronoun
Him; her; them (used as a relative pronoun to refer to a previously mentioned person or people.)
He's a person with whom I work.;We have ten employees, half of whom are carpenters.Whopronoun
Whoever, he who, they who.
Whonoun
A person under discussion; a question of which person.
Whonoun
a United Nations agency to coordinate international health activities and to help governments improve health services
Comparison Chart
Who | Whom |
Usage | |
‘Who’ is used as a Subject in a sentence. | ‘Whom’, is used as the object. |
Structure | |
The pronoun ‘Who’ is placed in the middle of the sentence to provide detail about the subject | ‘Whom’, also provides detail, but unlike ‘who’ for the Object in a sentence |
Co-relation | |
‘Who’ can never come as Object | ‘Whom’ can never be used as a Subject |
Definition of Who
‘Who’ is a Relative Pronoun in the English grammar to play the role of a ‘connector’ in the middle of the sentences where it is needed to refer to the subject mentioned earlier in the sentence. This relative pronoun relates two parts of the sentences to make it as a whole complex sentence. Not only as a relative pronoun, ‘Who’ is also put at the start of the sentence, but in such situation where to seek some information in the interrogative sentences. ‘Who’ can only be used as the subject of the verb and that it can never be employed as an Object of the verb in the sentence.
Definition of Whom
‘Whom’ is another relative pronoun in the English grammar which is also used to related two parts of a sentence. However, unlike ‘Who’, ‘Whom’ can only be used as the object of the verb instead of Subject in the sentence. It can either be used as ‘Direct Object’ or ‘Indirect Object’ in a sentence, not only for Affirmative sentences but also for the Interrogative ones. For instance, as a direct object, ‘Whom are you following in life’? as an indirect object, ‘To whom was the dog running after’?