Encryption – Why Bitlocker requires a partition on some computers but not all

We have identical HP desktops.

I configured Bitlocker encryption on a computer, no partition was required and the computer was fully encrypted.

The second computer gave me a different result, Bitlocker needed to partition and reduce the drive to 800 MB. After that, the computer was encrypted.

Disk Management displays the partition created for Bitlocker and another computer without partition.

Why is Bitlocker doing this? Require a partition on one computer and not on another?

Second Computer: Created Partition – Fully Encrypted
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First computer: no partition – fully encrypted
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