Classified advertisement and Newspaper ad

Classified advertisement noun - A short ad in a newspaper or magazine (usually in small print) and appearing along with other ads of the same type.

Newspaper ad and classified advertisement are semantically related. In some cases you can use "Newspaper ad" instead a noun phrase "Classified advertisement".

Newspaper ad noun - A printed advertisement that is published in a newspaper.

Classified advertisement and newspaper ad are semantically related. Sometimes you can replace phrase "Classified advertisement" with "Newspaper ad", this phrases are similar.