The key difference between the Paris Visite and the Passe NavigoDécouverte is the ability to synchronize with the days of your visit and the price.
A week with Navigo costs more than with Paris Visit, but the Navigo weekly pass must be purchased the Friday before the week of validity and sales end on the Thursday of the week for which they are valid.
Cumbersome and confusing instructions for those who visit. The Navigo is designed for residents, the Paris Visite for the comfort of the visitor.
With the Navigo you can get on: public network buses, metro, RER (trains), tram, Noctilien (night buses), Orlybus and Montmartre Funicular.
With the Paris Visit you can get on:: public network buses, metro, RER (trains), trams, Orlyval, Noctilien (night buses) and Montmartre Funicular.
If you still want to know more about Navigo, check out the official page. To buy the Paris Visite pass you only have to use the machines in the stations or the ticket offices with a vendor in the train and metro stations.
Attention: To use the metro and buses, there is an economic option that would be the single ticket, it is called Pass Ticket t+.