Good day She plays outside some of the time. In this example she would have a one hour break and she will play for some of that hour outside, let´s say 20min. I play outside sometimes. This means that I play outside every once in a while, on different days or at different times. I hope this helps. Kind regards Nicci

There isn't much. "Sometimes" suggests multiple moments or instants in time. "Some of the time" suggests a long period of time with something happening during (say) 25% of that time.

With an adverbial meaning, they are similar but ‘sometimes’ is more common. ‘Some of the time’ sounds more probabilistic. This is because ‘some of the time’ has a noun meaning referring to a specific time. /Sometimes/Some of the time/ he’s a jerk. (adverb) If your commute takes an hour, be sure to use some of the time to listen to podcasts in English. (Noun)