The difference between a noun and a pronoun is the difference between calling someone by his actual name and hollering out "You!" in a crowded store. Nouns refer to persons, places or things. Pronouns take the place of nouns. Instead of repeating a noun throughout a sentence, you use a substitute pronoun. Nouns define the subject. Using pronouns means you don't need to continually repeat the noun.
A noun refers to any named person, place or thing. An example of persons include men, women, boys and girls. Places include towns, restaurants, houses and businesses. Animal nouns such as dogs, cats, horses and bears fit this category as do statues, toys, boxes and cars. If you do not use pronouns in your writing a sentence might look like this: "The cat chose to sneak out the front door where the cat almost got hit by a car before the cat ran home to eat the cat food waiting in the cat bowl." Nouns can be singular as well as plural such as dog or dogs or collective as pack, herd or committee. Nouns also include abstract concepts such as love, goodness, faith and idea.
Proper nouns put a name to a general description. A little boy becomes Ben; a little girl becomes Sharita. A dog takes on the name Midnight, and the cat answers to Cutie. Proper nouns take generalities and put names of people or places on them such as Minneapolis and Chicago, President Lincoln and Senator Zorinski. A proper nouns starts with a capital letter. Pronouns substitute for specific proper names.
If pronouns didn't exist you'd insert the name of the person, place or thing every time it was referenced. "John said John wanted to practice playing the music John had written." Pronouns allow for a more natural cadence of language. Pronouns help create a more natural flow of communication with the use of noun substitutes. Adding pronouns, the above sentence more naturally reads, "John said he wanted to practice playing the music he had written."
More Pronoun Substitutes
Personal pronoun substitutes include she, he, I, it, you, they, us and we. As Sara (a proper noun) walked down the aisle toward Albert and Dan (both proper nouns), she (a pronoun substitute for Sara) smiled. Possessive pronouns refer to ownership such as hers, his, mine, ours and theirs. Unlike nouns, pronouns ask questions with what, which, whom and who, questions journalists ask when researching a story or when a detective seeks to discover the perpetrator of a crime. Some pronouns identify or target a person, place or thing with the use of that, these, this and those. "This is the person who did the crime." "Those two are brothers."