Reflect on-means thinking of what happened in the past Contemplate-means to second guess and rethink about something . Ponder-means to think for a long period of time and to think of something very carefully. Ruminate-means to think deeply about something. (These words have similar meaning ,in the English language we call these words synonyms)

Hi Lilith I hope this helped. Have a great day💫.

They are all quite similar. I think seeing them in context would clarify the differences.