What is the difference in risk of pregnancy between taking the pill a few hours late and a day late before unprotected sex?

Can’t quantify: Pills work best when taken as directed once per day. Taking one a few hours late makes no difference. If you miss an entire day then according to the package instructions you take two the next day to limit the risk of pregnancy. There are easier, more effective, nondaily methods for birth control you may want to consider such as an IUD, Nexplanon or Nuvaring