thumbtack vs. pushpin

a tack with a large, flat head, designed to be thrust into a board or other fairly soft object or surface by the pressure of the thumb.

to attach or tack by means of a thumbtack.

a short pin having a spool-shaped head of plastic, glass, or metal, used for affixing material to a bulletin board, wall, or the like.

an early children's game.

Archaic. child's play; triviality.