Chardonnay and Riesling are two of the most famous white grapes. In most cases, restaurants will have both. The differences in Style & Taste is due to the sugar, acidity, flavors & bouquet. Chardonnay is usually aged in Oak Barrels (can get un-oaked) and Riesling is fermented in stainless steel vats or neutral casks. The most widely celebrated Rieslings are from the Clare Valley for the drier side to the wine and Langhorne Creek produces great whites too with Chardonnay.