If nothing else, the massive Equifax data breach should broaden our knowledge of how credit bureaus work.

For example, until this cybercrime exposed 143 million consumers to identity theft, many people didn’t realize they could freeze their credit to block new lenders from seeing their reports if they suspected they had been victimized. This helps prevent thieves from opening credit in someone else’s name.

In response to the breach, Equifax is now offering a year of free credit monitoring through its identity-theft prevention service, TrustedID Premier. The service gives you the option to freeze or lock your credit with Equifax, but not for the other two major bureaus, Experian and TransUnion, or the lesser-known Innovis.

What caught my attention was a note from Equifax that you can either lock or freeze your file, but you can’t do both.

So what’s the difference?

The difference apparently comes down to the ease and speed with which you can open and close your credit file. The bureaus make locking sound like the better choice, but is it?

Although the freeze is separate, the bureaus have created a lock as part of a service package that includes credit monitoring and other things meant to prevent or detect identity theft. Frankly, I’m still confused at why there’s a need for a lock. It’s just one more thing for us to figure out about an already opaque system.

Experian’s “CreditLock” is a feature in its “CreditWorks” service, a monthly subscription that offers credit monitoring and gives access to your FICO credit score. In the description of its TrustedID credit lock service, Equifax says requests to lock or unlock a credit file are fulfilled within 24 to 48 hours.

TransUnion, meanwhile, offers a lock through its free “TrueIdentity” product, which also has its own app.

Blumberg said consumers can unlock their accounts free of charge by using the app or going to TrueIdentity.com. But free doesn’t come without a catch.

“You understand that in order to receive the free products, you must agree to receive targeted offers by TransUnion and other third parties,” the agreement says.

Most state laws require a credit freeze submitted by mail to be lifted within three business days. But it can be much shorter – as little as 15 minutes – when done electronically.

I was still not sure there was a big-enough difference for me to pay a subscription fee or subject myself to upselling, so I asked Brian Krebs, founder of the cybersecurity site Krebsonsecurity.com, what he would do.

“Do the freeze. Forget about the lock,” Krebs said in an interview.

One of the reasons some might have balked at getting a freeze is the delay that unfreezing can create in getting credit approved. The speedier credit locks could seem to be an answer to this concern. The question you have to ask is: What’s that convenience worth?

And I’m left wondering why the bureaus don’t provide the same ease for a credit freeze.