There's really no difference between jail and prison. It's just used interchangeably in American english. Now a county jail/prison compared to a state or federal? Yeah you normally don't have hardened criminals. Most people know each other since it's pretty local, and from what I've heard most are usually serving a year or under.
Jail and prison are different, legally, and while the facilities are similar, they tend to have a very different population, culture, and general vibe.
When people say "County", they mean jail. When people say "State" they mean prison. There is generally no such thing as a county prison, as those are handled by the state board of corrections.
"Federal pound-me-in-the-ass" prison is a pop culture misnomer as federal prisons are often much better places to be than state prison, because they're usually better run, better organized, lower population, and tend to not have people who are randomly violent, since almost all violent crime is prosecuted on the state level. The few violent federal inmates tend to get separated into high-security facilities vs. the nice prisons where the tax evaders go.
In Jail there are four groups of people, and they only intermingle somewhat.
1) People who are there for a day/weekend because they're getting booked and then bailed out. They often won't wind up even talking to another person. In older jails they used to be housed together in temporary group holding cells organized by type, but in more modern jails this is not the case anymore and instead they get individual small cells while they're sorted out.
2) People serving short sentences (the "year or under" you mentioned. In most states one year is the dividing line between jail and prison, though in some it's a little different). This is the part that's most like a prison, but unlike a prison, everyone is there for petty crime.
3) People who can't make bail and are waiting for trial, generally because they're too poor. Bail reform in some places has made this population pretty small, and they get housed with group 2 a lot.
4) People too dangerous to release while they are waiting for trial and thus are denied bail. The dangerous people are usually kept separate, even from each other, though each jail is run differently. Technically Chris is one of these people.
More importantly, in jail almost all the population are locals. Though there are states like California where they had to ship people around due to overcrowding. Generally though for instance if you live in a rural area you're not going to run into an urban street gang, etc.
So yeah, when normies talk they often don't know the difference between jail and prison, but it's actually functionally very different. It's like with firearms -- normies use "clip" and "magazine" interchangeably, but if I'm buying a rifle with a clip-fed magazine vs. one with a detachable magazine, they have very specific and different meanings.
Even if Chris were housed with population 2 from the list above, he would not get shanked. The rural jail wouldn't have a gang organization that could manage weapon distribution and the social cohesion necessary to cover for such an act, and the people he'd encounter wouldn't be people in for drive by shootings or stabbings. He'd be in with shoplifters and drunk drivers. He might get punched by someone who was in for a bar fight, though presumably that person would be sober and not want to add another charge and get themselves six more months.