Rosin versus resin

Rosin versus resin:

Resin can be any solid or highly viscious substance from plants, or synthetic analogues, that will set into a hard lacquer or enamel-like finish.

Rosin typically refers to one of a few specific resins.

For example

Rosin on on violin bows is often often pine tree sap, heated and concentrated.

rosin/resin soldering flux

See also Electronics project notes/Common terms, useful basics, soldering#On_flux

THC rosin is heated, concentrated sap from the cannabis plant.

though there is a more specific resin/rosin distinction in this context