In modern tufted rugs, the thread is threaded into the backing, the tufting cloth, fixed in place with latex, and finally provided with an extra backing of fabric or foam to reinforce the carpet.
The pile thread of tufted rugs can be cut or uncut (loop pile) or a combination of both. Tufted carpet is much faster and cheaper to make than woven carpet. As a result, it is often cheaper, but it can be of the same quality.
Nevertheless, pricing in tufted rugs can vary a lot based on the used materials and tufting density.
Material
Regarding material: Always buy the best quality you can afford. Especially with hand tufted rugs, cheap is expensive, because it generally stains and wears more quickly. For more details see tbe blogpost on fibers and yarn.
Density
The texture and quality of a tufted rug depends on the way it is manufactured, the finish and the type of backing applied. You can test the pile density by folding a swatch of the rug in half, with the pile facing you. The less visible of the backing, the stronger the rug. A higher desity means better quality, but ofcourse also that more yarn is used and was therefore more expensive to make.