e$.$Explain why the following two queries give different output for the data currently in the shedspace database.

Query A

SELECT MachineType.TypeName, COUNT$($Machine$.$SerialNumber$)$

FROM MachineType JOIN Machine

ON MachineType.TypeName $=$ Machine.TypeName

GROUP BY MachineType.TypeName;

Query B

SELECT MachineType.TypeName, COUNT$($Machine$.$SerialNumber$)$

FROM MachineType LEFT OUTER JOIN Machine

ON MachineType.TypeName $=$ Machine.TypeName

GROUP BY MachineType.TypeName;