I have twin boys. they are raised in the same house, they have the same routine, play with the same toys, are treated the same and they are both at different stages of development.
C crawls - T doesn't
T has 2 teeth - C has none
T loves to chew food - C is finally starting to get the hang of it
C rolled over months before T did
T is more stationary while C is busier
C loves people while T is a bit more shy