Hi Robert,
here you can find the description of the three exam modes available in the PM PrepCast Exam Simulator:
www.pm-exam-simulator.com/features/three-exam-modes
I am also attaching a screenshot showing you the options to run a quiz mode (either timed or learning). I used it as a preliminary preparation while I didn't feel ready to go for a full exam, and I also found it useful to practice for the new exam with the built-in break: as you observed, there is no way to pause, so that was a nice alternative.
As Deepti mentioned, the database is the same, for both quizzes and exams, so — while the full exams do not overlap with each other — you may end up with repeated questions when answering the quizzes; i.e., you may encounter the same questions in other quiz sessions or in one of the full exams. For me it was not a big deal, but it's always good to keep that in mind.
Gabriella