This paper compares two market structures, namely auction and dealership markets defined respectively as centralized order-driven and fragmented quote-driven markets. Our approach departs from previous works comparing these market mechanisms by considering both the timing of order submission (quote versus order-driven) and trading concentration (centralized versus fragmented) as dimensions di.erentiating these trading structures. We compare markets using measures of market viability, informational e.ciency, price variance, informed trading aggressiveness and market liquidity. We find that this approach changes dramatically the results of previous works comparing these trading structures. Indeed, we prove that auction markets are less sensitive to asymmetric information problem and they exhibit higher level of informational e.ciency than dealership markets. Moreover, we find that the relative magnitude of price variance, informed trading aggressiveness and market depth in both structures depend on the market thickness.