"The difference between a semimonthly and a biweekly payroll is that the semimonthly is paid 24 times per year, and the biweekly is paid 26 times per year. A semimonthly payroll is paid twice a month, usually on the 15th and last days of the month. If one of these pay dates falls on a weekend, the payroll is instead paid out on the preceding Friday. A biweekly payroll is paid every other week, usually on a Friday."
https://www.accountingtools.com/articles/what-is-the-difference-between-a-semimonthly-and-biweekly-pa.html