What is the difference between such password protection and bitlocker protection? Is there any difference in protection level?
An answer requires information that we do not have. The vendor would need to publish details on their crypto implementation in order for us to assess it fairly. I would go with Bitlocker on any drive where such information is not available.
1. The quality of Bitlocker is known. It has a good algorithm and a good implementation (uses AES, is FIPS certified).
2. The compatibility of Bitlocker is excellent. It works seamlessly on any modern version of Windows, and it requires no special drivers or software that may be blocked by antivirus. It can work under Linux with Dislocker---not sure if the HD vendor's application will support Mac or Linux.
3. Bitlocker is extremely flexible, with multiple options for key protectors and recovery.
If you want to use Bitlocker, it will take time to encrypt the drive. However, you should be able to read and write from the drive during the encryption process.