Demonstrative pronouns (this, that, these, those) substitute for things being pointed out. Examples: These are the pizzas you ordered. (demonstrative pronoun)
Those pizzas you ordered are very hot! (adjective)

Indefinite pronouns (each, either, neither, one, anyone, somebody, everything, all, few, many, etc.) substitute for unknown or unspecified things and frequently precede prepositions. Avoid mislabeling the object of the preposition, which modifies an indefinite pronoun, as the subject, direct/indirect object, or subjective/objective complement.
Examples: He gave some of the students extra credit. (pronoun as indirect object)
He gave me some money. (adjective)
Most in the courtroom agreed with the jury’s verdict. (pronoun as subject)
Most people don’t want to do jury duty. (adjective)
Grace became one of the best photographers in her class. (pronoun as subjective complement)
Grace is one class away from her photojournalism degree. (adjective)

Note: Relative, demonstrative, and indefinite pronouns are often difficult to distinguish from adjectives. If the word describes a noun, which it often precedes, it is an adjective. Otherwise, it is a pronoun.

Interrogative pronouns (who, whom, which, what) ask questions.
Examples: What do you want? (interrogative pronoun)
Which of the students wrote this paper? (interrogative pronoun)
Which student wrote this paper? (adjective)