Allen Bradley Safety Inputs vs Safety Pulse test/Test output

I see how the safety test pulse/test output works but what makes a safety input a safety input? We use safety pulse test/test outputs for push buttons and contact closures and safety inputs for proximity sensor inputs and such. I just don't really see how a safety input is any better than a standard input other than the safety processor having the companion processor. Could someone elaborate on this?

Safety input card can have tests and diagnostics of the input card. eg. it will disconnect the input, connect it to 24V and make sure it gets the expected result.
Safety input card and safety sensor will have a 'probability of failure safe condition' and 'probability of failure unsafe condition' that can be used for safety reliability calculations.
Safety input card can have two channels for the one input for comparison.
If using a semiconductor input, (ie. not relay contacts) the card can monitor for: short circuit to 0V/24V and open circuit.

Also, there are administrative controls so that additional procedures must be followed for any modifications involving a safety input.