Pad and Papyrus

Pad noun - A number of sheets of writing paper glued together at one edge.

Papyrus and pad are semantically related In some cases you can use "Papyrus" instead a noun "Pad".

Papyrus noun - Tall sedge of the Nile valley yielding fiber that served many purposes in historic times.

Pad and papyrus are semantically related in material upon which one writes topic. You can use "Pad" instead a noun "Papyrus".