Resin is a natural plant secretion, while tar is made by heating organic material until it breaks down. Pine resin can help make pine tar, but resin and tar are not the same thing.
Resin is produced by living plants, especially conifers, as a sticky protective substance. It can flow from wounds, harden on bark, and be collected for uses such as rosin, turpentine, varnish, incense, and traditional craft. Tar is different because it is produced by heat-driven decomposition.
That difference matters. Pine tar may come from resin-rich pine roots or wood, so it carries a resinous character, but it is not simply pine resin in a tin. The wood has been heated in low oxygen, producing a complex smoky material.
Resin tends to be lighter, more plant-like, and closer to the living tree. Tar is darker, smokier, and more transformed. Resin can be distilled into turpentine and rosin. Tar can be refined, separated, or thickened into pitch-like products.
The short answer is that resin comes out of the tree, while tar comes out of a heating process. They are related in pine-based industries, but they should not be used as interchangeable words.