A part is a noun phrase that refers to a part or piece of something. It is made up of the article “a” and the noun “part”. For example:

• She played a part in the play.
• He wants to keep a part of the cake for himself.

Apart is an adverb that means separate or distinct from something else. It can also mean into pieces or sections. For example:

• They are sitting apart from each other.
• She tore the paper apart.

In summary, a part is a noun phrase that refers to a part or piece of something, while apart is an adverb that means separate or distinct from something else, or into pieces or sections.