How it is different to define a person
than it is to define a word?

It’s different to define a person than it is to define a word because defining a person means to describe them where as you don’t really know them personally. Defining a word owns up to its true meaning. With a person you can’t define them because you never know how well you actually know them

I think the answer you are looking for is...He should putt it in the beginning of his essay.