are laws different in each state?

I am hoping to get a good tax refund coming up and with it want to pay off some debt.

I had someone very rude call me and it scared the heck out of me. But I am not sure what the laws are. What happens if you live in NH, but the law office trying to collect the money is in MA, and the credit card company is from yet another state? Which state laws apply in this case?

Can you be sent to jail for not paying a debt? Or can they just have a judge insist you pay by a certain date?

With the money I get I was wanting to start paying things off, but I am sure it will only cover a little bit. As long as there is no real possibility of being sent to jail, I'd rather pay the places that have not been hounding us and being very rude and intrusive first. And work my way down to those rude companies last. But they make you feel threatened, and so I am wondering exactly what can happen when they say they are going to tell the lawyers to pursue and take action. What does that mean they will do?

We do own a home, but have hardly any equity since we've only been here a few years.

My major worry is jail. Is that ever something they can do?