Keyes alike locks means that regardless of the quantity you order, all locks on the order will operate from the same key as every other lock on the order. For instance, if you order 3 locks, each lock will come with 2 operating keys which means there will be a total of 6 keys what will operate the 3 locks.
Keyed differently means that for each lock you order, none of them will operate from another locks key and only the 2 keys included with the lock will operate that once specific lock.