Is chirality absolute or relative? While going through some questions on chirality and optical isomerism, I came across this compound:

Note that I have marked 3 carbons as $C_1,C_2,C_3$
Its obvious that $C_1,C_3$ are chiral carbons.
$C_2$ is not a chiral carbon as it has the same group above and below it( With respect to the picture)
However a thought struck me that chiral carbon meant that 4 different groups are attached to it.
But what exactly does same group mean?
Does it mean that even the spatial arrangement of the groups should be different?
Or does it not matter?
So if spatial arrangement mattered, then the compound I have mentioned would have a chiral $C_2$ carbon for specific configurations around $C_1$ and $C_3$ carbons.
Yes, spatial configuration of attached groups matters. Meaning different stereo configuration of $C_1$ and $C_3$ may render $C_2$ either chiral or not:

Also because you have more than 1 stereo center you're not limited to just enantiomers, you can get diastereomers - the molecules will be different even though they're not mirror images of each other: