How does column-oriented NoSQL differ from document-oriented?

Question

The three types of NoSQL databases I\'ve read about is key-value, column-oriented, and document-oriented.

Key-value is pretty straight forward - a key with a plain value

Answer 1

I would say that the main difference is the way each of these DB types physically stores the data.
With column types, the data is stored by columns which can enable efficient aggregation operations / queries on a particular column.
With document types, the entire document is logically stored in one place and is generally retrieved as a whole (no efficient aggregation possible on "columns" / "fields").

The confusing bit is that a wide-column "row" can be easily represented as a document, but, as mentioned they are stored differently and optimized for different purposes.