Clarifying the role of Appointments, Bookings, Events + Marketpress

Hi

I am trying to understand the advantages / disadvantages of the various combinations of plugins available for CRM.

Events + Marketpress integration = allows people to 'sell' events to the public. From my understanding this lets people book tickets to events.

Appointments = allows a person who sells a service (such as web design or hair stylist) to have clients book their future time slots

Bookings = ??

What's the difference and pros and cons and the various combos for them all?

Thanks for any clarification.

Cheers,

Johnny