The retargeting component includes taking the data in your CRM and syncing it with third-party sources for cookie- or IP-based targeting. If you know the name of an account you want to target, and this account is in your CRM, then additional platforms (such as AdRoll and LiveRamp) match your data for CRM retargeting.
Account-based marketing platforms add another layer onto CRM retargeting with account-based retargeting. Account-based retargeting proactively targets the entire set of people in the account. CRM retargeting uses the first email or contact who came to your website.
Because Bob from ACME came to the website, he is the first contact associated with the account in your CRM. You know Bob isn't the only decision-maker in the account. If Bob is a Marketing Manager, you need to find Bob's Director of Marketing or CMO. Your ABM platform will use Bob's company name, ACME, and find more contact data for the marketing team members at ACME. This way, the entire marketing department at ACME will see your advertisement. This helps to expand your reach in your target account.