Tree Sap
All trees produce a "sap", to some degree. Tree sap is a translucent, thin, watery, slightly amber-colored substance (just a tad thinner than standard honey) that develops within the xylem and phloem cells of the trees. These cells are responsible for transporting water and nutrients throughout the tree, and carry water, hormones, sugar, and other mineral elements.
As a result, sap contains sugar and water, and is extracted from trees using buckets and spiles. Maple syrup comes from the sap of Maple trees. A tree uses sap in two ways: either it pulls sap from the water in the soil and sends it out through its leaf pores (stomata), or sap flows down off the leaves towards the roots, because it contains the vital sugar (food) the tree synthesized in its leaves during photosynthesis.
Tree Resin
Also known as "pitch", tree resin is thicker, tackier, and darker than tree sap. Deciduous trees do not make resin; it is only produced by trees that belong to the Pinaceae family, such as pine, fir, and cedar. Resin forms in the outer cells of the trees, also known as the inner and outer bark. Outer bark is also known as the phloem. You can make a cut into a resin-producing tree, and see the resin ooze out of the bark. The resin is meant to work like a scab; it closes up the wound and protects it from outer elements while it heals.
Resin is sticky and clear, and composed differently than tree sap. It is composed of compounds secreted by or deposited in the tree and sometimes contains high levels of chemical properties. For this reason, it is used for a variety of commercial and industrial applications; maple syrup is not one of them. Resin is used to manufacture commodities like ink, lacquer, varnish, jewelry, perfumes, and many other commercial products.