Difference between Demonstrative and Relative Pronoun

Demonstrative pronoun points to a person or subject which is at a distance from you and you would highlight the distance between you by saying so. For example, let’s say you and one of your classmates is sitting on a coffee table and you see that there is another person sitting at one corner of the cafe and you recognize him. So you would introduce to your friend as “that guy at the corner used to be my batch mate during my school days”. Now when you walk up to the guy and introduce your friend you would say “This guy is my best buddy”.  These kinds of pronouns imply a special stress in spoken English. Demonstrative pronoun may sound like a demonstrative adjective but is used differently in the sentence. It acts as a pronoun taking the place of a noun.

Relative pronouns are used in complex sentences where it introduces a subordinate clause. In such cases you do not show the distance between you and another person or object rather you point to subject of the action. In simple words that is used to combine two different sentences into a single sentence. Let us consider the two sentences mentioned below:

•    I was preparing for the civil service examination.

•    I cleared the civil service examination.

Now using the relative pronoun that we can combine the above two sentences as follows:

•    I was preparing for the civil service examination that helped me clearing the civil service examination.

Relative pronoun provides more information to the sentence when used after the noun. The expanded form of relative pronouns is called as indefinite relative pronouns. For example, consider the below sentences:

•    He did whatever he thought was correct.

•    Whomever the boss thinks is sincere, will get awarded by him.