A paver patio should start out with a base of 3/4" crushed-rock gravel, which should be compacted. Over this goes a layer of coarse builder's or masonry sand that is watered to settle it and leveled. Then you lay the pavers over this base. Paver sand is very fine and is added after the pavers are laid, then brushed into the paver joints.

after prepping the base to lay on your pavers, the polymeric sand is the one that gets brushed in the joints and then misted. it will harden and help keep everything in place.

A regular sand on top would just wash away slowly.

Polymeric sand is a unique mixture of fine sands combined with other additives (polymers), that, when mixed with water, form a surprisingly strong binding agent that locks the sand particles together. ... The binders lock the sand particles together, which helps secure the pavers into a uniform, durable surface

There seems to be some differences in terms. You'd be more inclined to start with a sublayer (several inches thick) of crusher run gravel (infinitely mixed sizes from 1" down to dust) in the North. Over that and in the South, we use PAVER BASE sand. It is crunchy crushed concrete with some 1/4" bits down to sharp sand and dust. It is kind of like Grape Nuts cereal. All of this so far is base and is packed down hard and tight. Next comes a 1" setting bed layer of sand that is screeded out and is left undisturbed and uncompressed. It is not watered or packed down. The pavers are carefully set on it. After all the pavers are set and the edge restraint is installed, then the whole field of pavers is tamped down in several passes with a mechanical or manual tamper. After the first tamping, sand is swept into the joints. (It can be any kind of sand that fits; masonry sand is finest so is easiest to use. I've used that, play sand, and paver base sand, too. Since the latter has 1/4" bits that won't fit into the joints, they will be swept off at the end.) More tamping. More sand. Watering. Tamping. More watering and more tamping. You are done when no more sand can fit in the joints and no more compression can be achieved.

Polymeric sand (sand with cement) is a double-edged sword. If not handled according to directions, the cement in it can badly stain pavers. Let's keep in mind that for decades, regular masonry sand was the "go to" sand to sweep into joints. Was it that bad? No! It works fine. And it doesn't wash out except under certain slope and running water conditions. (I have a garden shed without a gutter and the roof dumps water onto pavers and washes it out where it hits. But that's the only place and this year I'll get around to solving the problem with a gutter and downspout. Anyone who's been in business knows that there is a non-stop effort to create ways to charge more money by tweaking a product if one can. That's why there is not just spaghetti sauce, but 30 flavors of it. Pavers work fine without polymeric unless you have an unusual washing condition.