What is the ruling on differentiating between the quality of explanation in a school lesson and a private lesson?

A teacher must perform their required duties without falling short in explaining and clarifying, both inside and outside of school. Neglecting explanation inside school while perfecting it outside is considered a betrayal of trust and deception towards students and the school. However, if they perform their work diligently in both settings, and one of them becomes superior in quality due to reasons beyond their control, such as extended time or fewer students, then there is no harm in that.