Many people who start to work with Apache Solr or Watson Explorer have the first primary doubt about What is the difference from Field against Facet.
We can simple define that the field represent the indexed data, and the facet its such a GROUP, combined usually by volume. As described at Solr documentation “faceting is the arrangement of search results into categories based on indexed terms”.
Its possible to configure FACETS with many options like sort, searchable, etc. Each product have its possibilities.
Think that when you perform a query, you will use FACETs in the “Where”, something like this:
Select FIELDS from COLLECTION where FACET MY_FACET = ‘dummy’;
This will make you understand better!