Process is the term used for a complete load of the cube. All dimension and fact table data is read and all specified aggregations are calculated. You must process a cube when its structure is new or its dimensions or measures have been edited. Processing a cube can take a substantial amount of time if there is a large fact table and there are many dimensions with many levels and many items in each level. The loading of dimension information is not required if you use preprocessed shared dimensions in cubes.
Changes in the data warehouse schema that affect the structure of cubes require those cubes to have their structure changed and then be processed. Changes in or additions to data in the data warehouse do not require cubes to be completely processed. Such changes can be incorporated into existing cubes using the incremental update or refresh data processing options, depending on how the data changed.