In Pre-emptive scheduling, the highest priority task will keep getting

time to execute until it goes to waiting state or dead state or a task

with higher priority comes into queue for scheduling.

In Time slicing scheduling, every task gets a predefined slice of

time for execution, and then it goes to the pool of tasks ready for

execution. The scheduler picks up the next task for execution, based

on priority and various other factors.

https://www.careerride.com/Java-difference-preemptive-scheduling-time-slicing.aspx