Is this real or just a scam

It is a scam.  Police do not collect debts, they do not arrest people because they owe money.  Debtor's Prison went out over 200 years ago.  Threatening arrest is against the law.  These are criminals pretending to be debt collectors.  You need to read and learn what your rights are so that you don't become the victime of a crime.

This should start you out:
Federal law (FDCPA) requires them to send you a letter (US MAIL ONLY) within 5 days of their first contact that contains their name, physical address, the creditor’s name, and the amount of the alleged debt.  It also must contains “mini-Miranda” telling you that it is an attempt to collect a debt and that all information will be used for those purposes.  The one other important thing that this letter must also have in it is that you have a right to dispute the debt within 30 days of receipt of the letter and if you do so, all collection activity must be stopped until the debt is verified.
Read up on your rights here, get template letters to send and also make a complaint at this government site: http://www.consumerfinance.gov/

Also file a complaint with your State Attorney General's office.
List of State AG’s offices:  http://consumerfraudreporting.org/stateattorneygenerallist.php

They told me back in 2012 that I had taken out a loan for $470.00
I told them I didn't. Which I am for sure I did NOT take out this loan. They claimed someone did it online using my Social Security Number (They didn't know my ss# nor did I give it to them) All they had was one of my old emails that they said it was used with. I also believe this is bogus!!!!!!
The only thing scares me is my ex-wife has/had my ss# so I'm scared she really may have done this online. Since then I've taken out Identity Theft to alert me of someone trying to use my ss number or anything else.

Philline so am I. Since my divorce I've been trying soooohard to build my credit up. I think I've got scammed before. I've paid thinking it was a collection agency. So scared they would mess my credit score even worse. They told me it had been taking out online. I think it's a scam!!!!!

Do yourself a favor and read my post up there instead of asking someone who is as confused as you are.  Use the links to learn how not to be a victim of this type of crime.