Empty, vacant, blank, void, vacuous mean lacking the contents that could or should be present.
Something is empty which has nothing in it; something is vacant which is without an occupant, incumbent, tenant, inmate, or the person or thing it appropriately contains.
When qualifying the same nouns the words usually suggest distinctly different ideas; thus, an empty house has neither furniture nor occupants; a vacant house is without inmates and presumably for rent or for sale; an empty chair has no one sitting in it at the time; a vacant chair is one that has lost its usual occupant by death or other cause; an empty space has nothing in it; a vacant space is one left to be filled with what is appropriate.
Something, especially a surface, is blank which is free from writing or marks or which has vacant spaces that are left to be filled in.
Something is void which is absolutely empty so far as the senses can discover.
Something is vacuous which exhibits the absolute emptiness of a vacuum.
In extended use the same distinctions hold: an empty mind is destitute of worthwhile ideas or knowledge; a vacant mind lacks its usual occupant, the soul or intellect; a blank look is without expression; a person is said to be void of learning or of common sense when not the slightest evidence of either one can be detected; a vacuous mind, look, or expression is so deficient in alertness or spirit as to suggest a vacuum in its inanity.