classifier

As nouns the difference between classified and classifier

is that classified is a classified advertisement in a newspaper or magazine while classifier is someone who classifies.

As a verb classified

is past tense of classify.

As an adjective classified

is formally assigned by a government to one of several levels of sensitivity, usually (in English) top secret, secret, confidential, and, in some countries, restricted; thereby making disclosure to unauthorized persons illegal.

As nouns the difference between classifier and category

is that classifier is someone who classifies while category is a group, often named or numbered, to which items are assigned based on similarity or defined criteria.

As a noun classifier

is someone who classifies.

As an adjective multiclassifier is

that employs multiple classifiers.