They are quite different businesses.
Carillion was a building contractor that moved into facilities management.
Capita does 'business processes', i.e it does back office, as in running call centres.
It seems that Capita has a new CEO who doesn't like what he's seen and decided to do something about it. That £700m rights issue should keep them going if nothing else. Had the twonk who was running Carillion done something similar a year ago, Carillion would still be going.
P.S. Of course, as all readers of Private Eye should know, we are supposed to refer to the company as Crapita.