KML and KMZ are two extensions of the Geospatial information files used by Geographical Information systems and related software. They are used to record the attribute and other information about a location within a map.
KML
KML stands for Keyhole Markup Language. It was developed by Keyhole Inc. for their Keyhole Earth Viewer. A basic KML file is an XML file with specific notation for expressing geographical information such as annotations and visualizations in 2D and 3D geographical models available online.
Keyhole Inc. was acquired by Google in 2004 and Google products such as Google Earth and Google Maps were upgraded to support KML. KML was adopted as an international standard at the Open Geospatial Consortium in 2008.
KML files store geospatial data. KML files provide information to the relevant software regarding the features such as place marks, images, polygons, 3D models, and textual descriptions. These features are always incorporated with a specific coordinate on the map, often given by longitude and latitude. These files are also used to record the user interaction with features of the map for later use.
KMZ
The compressed version of the KML files is known as the KMZ files. KML file is an individual text format file while KMZ associates the data referred to in the KML files. These images and other data may be included in the compressed file in separate folders. A simple KML file can be compressed into a KMZ file by compressing it and renaming with the file extension .kmz.
A KML file is compatible with most of the GIS software while KMZ is supported by Google products; other software might not support.
KML vs KMZ
• KML and KMZ are two file extensions used for different instances of a Geospatial information file, known as Keyhole Markup Language.
• KML is a tag based XML language that is used to store attributes of a map or a model. Each KML file is composed of a collection of graphic elements, images, and settings.
• KMZ is a compressed version of the KML file.
• KML file is a simple text based file and can be opened in a text editor. KMZ file may be archived together with images and other information pointed in the KML file. These files can be stored in separate folders within the KMZ archive.
• Both file types are compatible with Google applications such as Google Maps and Google Earth, but other software might not support KMZ though they support KML.