sum vs payroll

sum and payroll both are nouns.

Word	Noun	Adjective	Verb	Adverb
sum	Yes	No	Yes	No
payroll	Yes	No	No	No

As nouns, payroll is a hyponym of sum; that is, payroll is a word with a more specific, narrower meaning than sum:

sum (noun)	payroll (noun)
the whole amount	the department that determines the amounts of wage or salary due to each employee
the choicest or most essential or most vital part of some idea or experience	a list of employees and their salaries
a quantity obtained by the addition of a group of numbers	the total amount of money paid in wages
the final aggregate
a set containing all and only the members of two or more given sets
a quantity of money

sum (verb)	payroll (verb)
determine the sum of
be a summary of