What is a constant voltage LED driver, LED driver constant current

 XI075C200V054BST1

Xitanium 75 W 2 A 54 V Output Max Linear LED Driver

https://www.futureelectronics.com/p/semiconductors--Led-lighting-components--led-driver-modules-rev--constant-current-acdc-led-drivers/xi075c200v054bst1-signify-north-america-5129716