In Pardot it's definitely not the same thing...
It seems so simple, doesn't it? Email Opt Out. Until you look at Pardot and see that there's 2 fields-- Do not Email and Opted Out. So what does each mean and how are you supposed to use them?
Let's start with what each field means.
Opted Out means that your prospect has explicitly said "don't email me" by unsubscribing in your preference center or using the unsubscribe link. When that happens your Pardot record looks like this:
In a Pardot list view, a record that looks like this will appear in BOTH the undeliverable and unsubscribed filters.
If an email hard bounces or has 5 soft bounces, it will be marked as Do Not Email only. This is because the person didn't actually opt out.
In a Pardot list view, this person will only appear in the "undeliverable" list filter.
The net effect of either one is the same, however. You will not be able to email this person in Pardot.
There's a "hidden" third field, which does not appear on the prospect record but is important when we're looking at how to map to Salesforce: Pardot Hard Bounced. This means that the email couldn't be delivered due to the bounce-- which is what causes the Do Not Email field to be checked in the first place.
So, how are you supposed to map them to Salesforce?
Here's my recommendation:
This seems obvious on the face of it, so why have I seen this wrong so many times? Check your field mappings in Pardot in the prospect field mapping section to see what yours looks like.
One reason could be if you have a relatively "old" Pardot instance, that predated connector version 2, when the Pardot Hard Bounced field appeared in Salesforce. Some instances don't have opted out mapped to anything, or Do Not Email mapped to the Email Opt Field.
In any case, here's the rationale behind the suggested mapping:
Opted Out can be configured in the connector to allow Salesforce to override the opt out (opt someone back in, with limits), but must be mapped a shown for this to work. It's also useful in Salesforce to see that someone has said "Don't email me" which is what that synched field means.
If an email hard bounces, we want to know it, this is why connecting the hard bounced field and displaying it in Salesforce is important. Oftentimes Pardot is going to be the system that "discovers" the email has gone bad.
If either Opted Out or Hard Bounced is checked in Salesforce, the impact is the same-- you can't send email. So there's no real reason to show or even sync the do not email field. And that's why I recommend setting this up in this way.