Maltose and Cellobiose, as shown by their chemical names, are both disaccharides made of D-glucopyranose. Comparing the structures you can observe that both have a 1→ 4 glycosidic bond. Carbon #1 of one glucose unit is bonded to the oxygen of carbon #4 of the second unit. The difference between the two is that maltose is α(1→ 4) and cellobiose is β(1→ 4). As you study the two structures notice that in connecting the two glucopyranose units together to form cellobiose the second glucose unit was rotated 180 °, so that the oxygen bonds of both carbon #1 (β configuration) and carbon #4 are projecting up so that oxygen has the normal angular geometry. In order to see the glucose in its normal position, rotate cellobiose 180° about the x axis so that carbon #6 is in the back of the ring and projecting upward. Also, notice the sharp bend in the maltose at the glycosidic bond. Most text books do not represent the structure of maltose in a way that shows this bend. Both structures show the anomeric carbon (yellow halo) of the second glucose unit as the α anomer, but in an aqueous solution that designation would not be significant because there would be an equilibrium mixture of the α and β anomers and the open-chain structure. Since the open-chain structure is present in an aqueous solution, an aldehyde group, which can be oxidized, is present so maltose and cellobiose are reducing sugars.

The difference in the configuration of the glycosidic bonds in these two sugars is important in digestion in humans. The enzyme maltase is present in the GI tract of humans, catalyzes the hydrolysis of the α glycosidic bond in maltose, but is not able to cleave the &beta isomer, as a consequence humans are not capable of digesting cellobiose.