None of them is offensive.

Technically, a smart person is an educated person, someone with a lot of knowledge. This knowledge may come from education or experience, but it's there.

A clever person is someone who can figure out almost any situation. It doesn't necessarily mean he has the required knowledge, but he's handy, so he can always solve whatever comes his way.

Should I over-emphasize this, just for the sake of your better understanding the difference, a smart person knows the theory, a clever person knows the practice.

Neither of them is offensive.

Technically, a smart person is an educated person, someone with a lot of knowledge. This knowledge may come from education or experience, but it's there.

A clever person is someone who can figure out almost any situation. It doesn't necessarily mean he has the required knowledge, but he's handy, so he can always solve whatever comes his way.

Should I over-emphasize this, just for the sake of your better understanding the difference, a smart person knows the theory, a clever person knows the practice.