(n): an essential and distinguishing attribute of something or someone
(n): a variation that deviates from the standard or norm
(n): an instance of change; the rate or magnitude of change
(n): a disagreement or argument about something important
(n): the speech act of disagreeing or arguing or disputing
(n): a significant change
(n): a relational difference between states; especially between states before and after some event
(n): the number that remains after subtraction; the number that when added to the subtrahend gives the minuend
(n): a concept of quantity involving zero and units
Here's a 'Spot the Differences' game that's challenging:
Crazy Monkey.