Different flavors are present in wine due to how the fermentation process occurs. When there is more skin, or tannin, present with the fermentation process it can leave a dry taste. This happens due to the natural sugars within the grapes will disappearing during the process because of the grape skin that is present.
Red wines tend to be more flavorful and tart in taste, and rarely are found to be sweet. Typically rosé and white wines are sweeter across the board, but this is not always the case when selecting wines. There is a label on the back of most wine bottles that will tell you the sweetness scale, from 0 being dry all the way up to 7+ which is very sweet.