Tar is usually the more fluid dark product from heating organic material, while pitch is usually thicker, more solid, or the residue left after tar is further heated or distilled. Historical usage varies.
Tar and pitch are closely related, which is why the words are often confused. In a simple modern explanation, tar is the dark liquid produced during destructive distillation of wood, coal, or similar material. Pitch is the thicker, stickier, more solid material that can remain after lighter parts are driven off.
The distinction is useful but not absolute. Older trades used words according to local practice, not modern chemistry. A sailor, roofer, tar burner, chemist, and dictionary might draw the line differently. Some materials sit between tar and pitch depending on temperature: firm in cold weather, flowing in heat.
In maritime work, both mattered. Tar could treat rope and surfaces, while pitch could help with sealing and caulking contexts. Tar pitch is therefore not a contradiction but a sign that tar can be processed into heavier fractions.
The easiest rule is this: tar flows more readily, pitch is more solid. When reading old sources, check the context before assuming the words match modern product categories.