なさいCommand to do

The dictionary/non-past form of a verb + な expresses a blunt command not to do something. In contrast, a verb stem + なさい expresses a strong but respectful command. For example, 食べるな means 'Don't eat it!' while 食べなさい means 'Eat it!' Despite being derived from an honorific verb, なさい is still a command and is used with lower-status people or children, not superiors.

ないでください is a polite way to ask someone not to do something. It is relatively neutral, and could be used with strangers or people equal in status to you. In contrast, なさい is a command form, similar to the English 'Do (this),' typically used when one person is in a higher position, such as teachers to students, adults to children, etc.

てください and なさい are both used to tell or ask someone to do something in Japanese. てください is a polite request, similar to 'Please (do this),' and is appropriate in neutral or formal situations, such as with strangers or people of equal status. なさい, on the other hand, is a firm command, closer to 'Do (this),' and is typically used by someone in a higher position, like teachers to students or adults to children.