http://cleminfostrategies.com/whats-the-difference-between-prison-and-jail/ Basically, a jail is for people who have been arrested and are being held pending a plea agreement, trial, or sentencing. A prison is a secure facility that houses people who have been convicted of a felony criminal offense and are serving a sentence of (typically) 1 year or more. How are these differentiated in Hebrew?
It isn't always differentiated in English either. In Australia we don't often use 'prison' (although we do use the word 'prisoner') and almost always use 'jail' (or 'gaol'). We might possibly say 'he went to prison' (in the sense of its being an institution) but when referring to a specific building or holding facility we'd tend to say 'jail', regardless of the type.
In (US) English one doesn't need to say 'police officers' ... just 'police'. That should be accepted. 'Officer' might imply higher rank -- like in the military -- so it could, in fact, be inaccurate to say 'police officers' because it could imply that all of them were of a higher rank.
True, but that's more about courtesy to the individual so they won't give you a ticket ;) I can't imagine saying 'there are police officers at the prison". "Guards", yes; "Police", maybe but that's not what people generally call those who work at prisons; "Police officers", no.