He asked what is the difference, and I would say none - both are to be avoided!
That said, I sometimes leave in the pin and sew VERY slowly, so slowly that if the needle starts to hit the pin I can tell whether it's going to hit head-on or slide to the side. And I'm glad that my old eyes need glasses, because they have provided protection more than once when I hit the needle plate. (Usually that happens right after I clean the machine. During cleaning I accidentally change the machine's setting to zigzag. I hate it when that happens!)