Part judgment, part acting, mostly accident. Baseball has no penalties at all. A home run is a home run. In football, on a score, you look for flags. Football acts can all be repealed.
Baseball acts stand forever.
Just when we thought there couldn't be anything worse than penalties, we get instant replays of penalties. Talk about a bad joke. Now any play, even one with no flags, can be called back. Even a flag itself can, after five minutes of boring delay, be nullified. NFL time has entered the Twilight Zone.