I think there are two very big differences here. Number one, according to the law as it stands, prisoners are entitled to receive OAS while they're in prison. They are not entitled by law to receive EI.
We do have a rigorous and very robust audit system within EI to make sure that anyone, wherever they are, whatever their circumstance...if they are abusing the system, for example, claiming funds and EI benefits fraudulently, they will be dealt with according to the law.