What distinguishes unsought, convenience, shopping, and specialty products?

"Unsought products are products unplanned by the potential buyer or known products that the buyer does not actively seek. Convenience products are relatively inexpensive items that require little shopping effort. Soft drinks, candy bars, milk, bread, and small hardware items are examples. Consumers buy them routinely without much planning. This does not mean that such products are unimportant or obscure. Many, in fact, are well known by their brand names—such as Pepsi-Cola, Pepperidge Farm breads, Domino’s pizza, Sure deodorant, and UPS shipping. In contrast to convenience products, shopping products are bought only after a brand-to-brand and store-to-store comparison of price, suitability, and style. Examples are furniture, automobiles, a vacation in Europe, and some items of clothing. Convenience products are bought with little planning, but shopping products may be purchased after months or even years of search and evaluation. Specialty products are products for which consumers search long and hard and for which they refuse to accept substitutes. Expensive jewelry, designer clothing, state-of-the-art stereo equipment, limited-production automobiles, and gourmet restaurants fall into this category. Because consumers are willing to spend much time and effort to find specialty products, distribution is often limited to one or two sellers in a given region, such as Neiman-Marcus, Gucci, or a Porsche dealer."