When you are locked up", you are locked in, you cannot get out until somebody opens the door from the outside despite whatever happens - unless of course you can break out. That could be a few hours in a police cell or a lifetime in a prison
When a prison or other institution goes into lockdown, nobody can get in or out until the lockdown ends - nobody.
In our present "lockdown'. thousands of people are flying into the UK every day, people can go out for excercise, shopping, work' people can travel in cars, on buses and trains; those with gardens can sit in them; people can use phones, skype, WhatsApp, Zoom and emails and internet - they can send and receive letters, order on line and take deliveries .... they can do so many things in their homes with the families or alone, they can cook, drink, watch TV at will
We are not really in a lockdown but we are restricted in our movements, said to be to protect ourselves and others from this virus.
Imagine being in prison, locked up, during this lockdown, or without this lockdown.
Having been through both, i choose this type of lockdown any day