Shared or Private
Shared is a guided tour (a local guide will be with you at all times) where you will share with other people you don't know. For example on a shared safari, you will share the safari vehicle. Generally shared safaris are for maximum 8 people. Departure dates and itinerary cannot be changed. The price is fix per person, no matter how many people are booking. Shared tours depend on availability.
Private is a guided tour (a local guide will
be with you at all times) where you will not share with other people you don't
know. For example, if you booked the tour for you and 3 friends of yours,
the tour will be only for the 4 of you with no other people. Private tours
can be from 1 person up to 20 people. Departure dates and itinerary are entirely
flexible. In general any itinerary can be completely customised and departures
can be any day of the year. The price depends on the number of people: more
people means lower price. Private tours are always available.