The distinction between the two lies in the depth and purpose of the action. Prüfen might be a preliminary check, while überprüfen often signifies a more rigorous and definitive assessment. For instance, one might prüfen a document for typos, but then überprüfen its legal accuracy. In everyday language, the terms are sometimes used interchangeably, but in more technical or formal settings, the nuance is important. The prefix "über-" in "überprüfen" emphasizes the act of going over something again, ensuring no errors have been missed or that a previous assessment was indeed correct. This iterative or confirmatory aspect is central to the meaning of überprüfen. Both verbs are fundamental to ensuring accuracy and reliability in various processes and situations.