Flavor vs Taste

Flavor Profile : The flavor profile of an item (food, sauce, etc..) is the balance of flavors that go into it. The primary flavors are : Sweet, Sour, Bitter, Salty. The Japanese claim there is a fifth flavor : Savory, which they call "umammi". Umammi comes from foods which are high in glutamates (MSG is the purest form readily available). Truffles are unusually high in glutamates. These four (or five) flavors are the only ones we can taste with our mouth. All other flavors are actually scents. The balance of the four basic flavors and how they relate is the "flavor profile" of the item. One can also discuss the added other flavors (which are actually scents) and how they relate to the primary flavors as part of the flavor profile.
Taste is one of those senses that we take for granted - until we get a cold. Then, it seems that we can’t taste anything. How we perceive taste is a complicated chemical process, and, it is closely linked to the sense of smell. Further complicating the issue is the idea of flavor. Taste is the information that our taste buds can tell us about what we eat. It is only one aspect of the flavor of a food. Flavor is a composite profile of a food based on its smell, mouth feel and temperature as well as its taste.
Remember the map of the tongue that your seventh grade science teacher passed out to you in class? Remember the areas for sensing sweet, salty, sour and bitter? Well, forget that. It turns out that the entire tongue, upper palate and even the inside of the cheeks have taste buds that can determine all of these flavors. While it is true that some areas of the tongue are more sensitive to certain tastes than others, the "tongue map" falsely leads people to believe that there is a strict differentiation among the different receptors, and this just is not the case.

What Happens When We Taste?

Here is what happens when we taste. First, we must smell - whether as a conscious deep sniff before eating, or just as scents waft up our nasal passages. Smell triggers an increase in saliva production in the mouth and a low-level increase in digestive acid production in the stomach. This prepares us to taste and digest our food. To taste anything at all, foods must be dissolved. Try putting a bit of food on your dry tongue. You won’t taste a thing.
Once food enters the mouth, its chemical components find their way to the taste buds. Some taste buds react most to the presence of sodium ions, and you will taste "salt." Others react mostly to sugars, acids, alkaloids or glutamates in the food resulting in tasting "sweet," "sour," "bitter," or "umammi."
Studies show that humans are hard-wired to like certain tastes and to reject others, most likely for survival. Sour and bitter tastes can indicate food that is bad, under-ripe or even poisonous. Sweet, salty and savory tastes indicate "good" foods. A sweet taste indicates foods that can give us energy—infants crave sweet foods, and lactose in milk is sweet. A salty taste indicates foods that can help us replace electrolytes lost through sweat or urination, and savory tastes can lead us to foods containing amino acids that the body needs.
Humans only recognize five tastes, but we can recognize thousands of smells. It is the way the brain puts together the tastes with the smells, temperature and mouth feel that creates our perception of "flavor." As much as 85% of the perception of taste comes from the sense of smell. Smells travel to the brain in two ways, up through the nostrils as you bring food to your mouth, and again through the "back door" once food is in the mouth, as some smells make their way up to the scent receptors through the pharynx.
While vanilla ice cream and apple pie both register as "sweet" on the tongue, their flavors are different because their smell, mouth feel and temperature are being processed at the same time as the tastes. The end result is the flavor of ice cream versus the flavor of apple pie.
When "smell" is taken out of the equation and mouth feel and temperature are similar, it is no wonder that an apple and an onion "taste" the same.