Preemption in Test 403c

Hi,

Can someone please explain, in test case 403c, why the transition for
"event1" is supposed to be preempted by p0s2 for the first transition in
p0s3, but is not supposed to be preempted for the same "event1" for the
catchall transition in p0s4?

In other words, what makes the transition in p0s3 different from the
transition in p0s4 so that it gets preempted? Also, for the sake of
understanding, is the transition for "event1" in p0s1 preempted?

Thank you