What makes the restart take longer than the shut down?

I have noticed that restarting my computer takes noticeably longer than shutting it down and turning it back on, and I cannot figure out why there is such a difference. Sometimes the restart screen stays visible for several minutes before Windows finally loads, while a normal shutdown seems much quicker. I have tried restarting a few times, but the delay keeps happening, and I am wondering whether updates, startup programs, drivers, or background processes could be responsible.