please explain CoreStorage

Hi,

could someone please explain the requirement and use of a CoreStorage volume. I ask this due to a difference in my two macs I dont understand.

Mac 1 is a 5K retina 27" iMac and the second is an early 2015 Macbook Pro both running release El Capitan.

if i run "diskutil cs list" on the Macbook Pro it lists the CoreStorage volume, if I run it on the iMac it shows no CoreStorage Volume found. The restore partition works fine on the iMac so there is no fault obvious. Thinking there was something wrong, i deleted all partitions on it, booted El Capitan from USB and reinstalled it clean. Still no CoreStorage volume so i am confused why there is a difference in the two macs.