No, the difference is that instead of the killer being sentenced to serve a term, they have the ability to improve themselves and deal with whatever it was that made them murder people without just being allowed to roam unchecked until their social problem is delt with.

I will also point out that these types of killers tend to have issues that arise from conditions created by capitalism (in this guy's case, he was a criminal who killed anyone who threatened to rat). Those holdouts need their traumas and driving conditions found and dealt with, especially if they're a literal life or death threat to the people around them.

The situation here is that the killer remains unrepentant and still desires to kill or shows no remorse for their actions. This alone means that they are likely to remain a threat too others if they are allowed to roam freely (by their own admission in this case). Which necessitates indefinitely detention in a facility that is humane and will continue working with the individual to find their specific issue and do what they can to help them back into general society.

Basically replacing all prisons with mental health centers, schools, and communal or cooperative workplaces. Environments where people can more easily reform themselves and not feel like they're under a punitive timeline, but have a goal of growth through education, remunerated labor, and therapies.

This concept is so far removed from the current carceral system in most developed countries now that the only way to get to it is through total abolition of prisons though. There is nothing of value to be salvaged from the American prison system except the conversion of the land these prisons sit on into parks, memorial, or farmland. I don't even think a new system should be built on the footprint of the old given that most prisons are so incredibly isolated from anywhere.