I don't think it is an aircraft swap, it's just that the schedule is a bit not straight forward, as well as there is more than one daily flight.
So on Tuesday you seem to get the 789 on KL695, or the 333 on KL691
Code:
Flight Timetables Search:
Search AMS to YYZ on 10/11/17 up to 7 days
Flight Stops Depart Arrive Aircraft Duration Frequency Effective Ending
KL 691 0 AMS 9:40 AM YYZ 11:35 AM 772 7 hrs 55 mins M,Th,F,Su 09/03/17 10/27/17
KL 691 0 AMS 9:40 AM YYZ 11:45 AM 333 8 hrs 5 mins T,W,Sa 07/22/17 10/28/17
KL 695 0 AMS 5:55 PM YYZ 7:50 PM 74E 7 hrs 55 mins M,W,F 10/09/17 10/27/17
KL 695 0 AMS 5:55 PM YYZ 7:50 PM 789 7 hrs 55 mins T 10/17/17 10/24/17
KL 695 0 AMS 5:55 PM YYZ 8:05 PM 333 8 hrs 10 mins Th 09/14/17 10/12/17