Rag paper and Writing paper

Rag paper noun - Paper made partly or wholly from rags.

Writing paper and rag paper are semantically related. In some cases you can use "Writing paper" instead a noun phrase "Rag paper".

Writing paper noun - Paper material made into thin sheets that are sized to take ink; used for writing correspondence and manuscripts.

Rag paper and writing paper are semantically related. Sometimes you can replace phrase "Rag paper" with "Writing paper", this phrases are similar.