I've noticed a fair few people differentiating between Marketo and CRM.
How ever my confusion comes when i try and delete a user from Marketo. It has a clear line;
Remove from CRM: true/false
Is Marketo in fact a type of CRM?
"Remove from CRM" means "Also remove from CRM," i.e. delete the lead not only from Marketo but also from whatever CRM system you've synced with Marketo using a native connector (SFDC, Dynamics, etc.).
In fact this checkbox confirms that Marketo and CRM are different.
Even if the lead didn't come from a CRM source? i don't agree with you that the checkbox confirms that Marketo and CRM are different.
They are. Please read the docs.marketo.com for this function.
This is a flow step that performs an Action on the Lead. It is giving you an option to also delete the Lead in the synced CRM, if you want. There are tons of threads on this, so do a search if you are curious.
To be more specific for your comment --- this flow action doesn't care about the Lead Source. You must select the leads you want to Delete with a smart list, only there should you determine the Lead Source or "System Source"
Even if the lead didn't come from a CRM source?
The person may have been synced from the CRM originally, or to the CRM after coming in via another source. Either way: "Remove from CRM" means "Also remove the record, if we know of one, in another system that's synchronized with this system."
i don't agree with you that the checkbox confirms that Marketo and CRM are different.
It does, otherwise it wouldn't exist. "Delete from this system, and also from this system?" would be the worst UI widget ever!
But it's already clear that Marketo is not considered to be in the CRM sector. Marketo shares some functions with CRM apps (so, too, do mailing list managers share functions with Marketo, but they're not Marketing Automation apps).
You asked and easy question, and it has an easy answer.
Is Marketo a CRM? No. It is not a CRM.
Bonus answer: SalesForce is a CRM, Microsoft Dynamics is a CRM. Marketo is a Marketing Automation System that can optionally, send data to a CRM. The option you mention simply allows you to not only delete from Marketo, but gives you the choice to delete from the CRM you have Marketo connected to (if you are using one), like Sanford said.
Here's a nice summary from Jon Miller (the founder of Marketo, now with Engagio): Big List of Marketing Automation Features - Marketo