Differentiating features of contusion (Vs postmortem staining) are -a) Bluish in colorb) Disappear with pressure on areac) Margin irregulard) Limited to intravascular compartmente) Extravasation of blood occurs
The colour of bruise changes as per stage of healing seen (whereas postmortem lividity as bluish-pink to bluish purple).
There is no effect of pressure on a bruise
Margins of a bruise are irregular and diffuse into surrounding (margins of postmortem lividity are clear-cut). 
In bruise, blood is into the extravascular compartment (it is in an intravascular compartment in postmortem lividity).
Extravasation of blood occurs in a bruise.
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