Is Mark a name or a noun?

The Word 'Mark' (capital M) is a name. A name is a noun.

The noun 'Mark" is a proper noun, the name of a specific person.

The Word 'mark' (lower case m) is a noun and a verb.

The noun 'mark' is a common noun, a general Word for a small area on a surface having a different color from its surroundings; a general Word for a line, figure, or symbol made as an indication or record of something; a Word for a thing.