CD-ROM drives are slower than Hard disk

Compact disk–read-only memory (CD-ROM) offers a balance between the portability of a floppy disk and the capacity of a hard drive. CD-ROMs are composed of a hard medium that contains very small depressed and raised areas, called pits and lands, respectively. CD-ROM drives read data from the CD using a laser instead of a read/write head.

And cdrom work in ATAPI mode were the HDD with LBA mode which has 16.6MBps

The speed of the cdrom is measured with x meaning

X= 150KBPS

And the hdd has 16.6MBPS and over with 7200RPM rotate speed