Biweekly payroll involves paydays that occur 26 times per year, such as every other Friday.
Semimonthly payroll refers to paydays that occur 24 times per year, such as paydays that occur on the 15th day and the last day of every month.
To illustrate the difference, let's assume that Company A and Company B each have a manager with an annual salary of $52,000. If Company A pays its employees biweekly, its manager's gross salary will be be $2,000 each biweekly pay period ($52,000 divided by 26 biweekly pay periods). If Company B pays its employees semimonthly, its manager's gross salary will be $2,166.67 each semimonthly pay period ($52,000 divided by 24 semimonthly pay periods).