@Woody Chiu at RASI, Thanks for posting in Q&A.
Based on my researching, Microsoft Defender for Business and Microsoft Defender for Endpoint are two ndpoint security solutions provided from Microsoft.
Microsoft Defender for Business is an endpoint security solution that was designed especially for small- and medium-sized businesses (up to 300 employees) to protect them from ransomware, malware, phishing, and other threats.
Microsoft Defender for Endpoint is designed for enterprises or businesses with more than 300 employees, and it is included in the Microsoft 365 enterprise plans.
Here is a link list the feature included in the two endpoint security solution for your reference:
To onboard devices to Microsoft Defender for Business or Microsoft Defender for Endpoint, there are many methods. For example, Windows 10 and 11 devices, you can choose Local script, Group policy or Intune. For Endpoint, it also has other method like MECM, VDI script.
To choose Intune to onboard devices to Microsoft Defender for Business, you can follow the steps in the following link:
To onboard devices to Microsoft Defender for Endpoint, here is a link with the detailed steps for your reference:
Meanwhile for your last question, I would say no, the device onboard to Microsoft Defender for Business will not in Microsoft Defender for Endpoint. As they are two security solutions.
Hope the above information can help.
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