What is the difference between cinematography and videography?
The answer is not that simple, but in general: videography is usually filming of unscripted events, such as weddings, while cinematography is filming of different scenes according to script.
However, certain documentary films may also consist of, or include, some previously recorded unscripted live footage - and videography sometimes includes scripted or acted scenes too, which are added during editing. It all depends on the needs. See samples below or go to the links above.

Some examples:

scripted documentary short preview

Tamil Children's Choir, Sri Lanka ‎(Ceylon)‎, scripted live footage, short excerpt from a documentary filmed in 2013

Green screen studio filming, 2011

"Dancing with the Longhouse People" ‎(excerpts)‎