What is the difference between Google Maps and Google Earth .KML and .KMZ file extensions? First off, both of these file extensions will produce similar results. The primary difference is one is compressed and the other is not.

The Google Earth KML file is a flat text-based file that is written using tags similar to such languages as HTML, PHP and XML. This file is generally a larger file size than a KMZ file.

SAMPLE / EXAMPLE SNAPSHOT OF A .KMZ FILE

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://earth.google.com/kml/2.1">
<Document>
    <name>TEST_0002_KML.kml</name>
    <Style id="sh_icon63">
        <IconStyle>
            <color>ff00ffff</color>
            <scale>1.1</scale>
            <Icon>
                <href>http://maps.google.com/mapfiles/kml/pal3/icon63.png</href>
            </Icon>
        </IconStyle>
        <LabelStyle>
            <color>ff00ffff</color>
        </LabelStyle>
        <ListStyle>
        </ListStyle>
    </Style>
    <StyleMap id="msn_icon63_copy1">
        <Pair>
            <key>normal</key>
            <styleUrl>#sn_icon63_copy1</styleUrl>
        </Pair>
        <Pair>
            <key>highlight</key>
            <styleUrl>#sh_icon63_copy1</styleUrl>
        </Pair>
    </StyleMap>
    <Style id="sn_icon63_copy1">
        <IconStyle>
            <color>ff00ffff</color>
            <Icon>
                <href>http://maps.google.com/mapfiles/kml/pal3/icon63.png</href>
            </Icon>
        </IconStyle>
        <LabelStyle>
            <color>ff00ffff</color>
        </LabelStyle>
        <ListStyle>
        </ListStyle>
    </Style>
    <StyleMap id="msn_bullet-section1_copy1">
        <Pair>
            <key>normal</key>
            <styleUrl>#sn_bullet-section1_copy1</styleUrl>
        </Pair>
        <Pair>
            <key>highlight</key>
            <styleUrl>#sh_bullet-section1_copy1</styleUrl>
        </Pair>
    </StyleMap>
    <Style id="sh_icon63_copy1">
        <IconStyle>
            <color>ff00ffff</color>
            <scale>1.1</scale>
            <Icon>
                <href>http://maps.google.com/mapfiles/kml/pal3/icon63.png</href>
            </Icon>
        </IconStyle>
        <LabelStyle>
            <color>ff00ffff</color>
        </LabelStyle>
        <ListStyle>
        </ListStyle>
    </Style>
    <Style id="sn_icon63">
        <IconStyle>
            <color>ff00ffff</color>
            <Icon>
                <href>http://maps.google.com/mapfiles/kml/pal3/icon63.png</href>
            </Icon>
        </IconStyle>
        <LabelStyle>
            <color>ff00ffff</color>
        </LabelStyle>
        <ListStyle>
        </ListStyle>
    </Style>

Now, as for a KMZ file, it is essentially a KML file that is compressed, which is why it is generally smaller than a KMZ file. When working in Google Earth, Google Earth Pro or Google Earth Enterprise, you can choose how you want to save the file and each of these file extensions is an option. Choosing to save a location or place or group of locations or places in the .KMZ file format will automatically compress the file.

You can also elect to format the location data as a KML file and then compress the file using a software application such as WinZip and save it as a .ZIP format. Once this is done, you can simply change the file extension from .ZIP to .KMZ, and your computer as well as your Google Earth browser interface will automatically read identify the KMZ file as a Google Earth compressed file and read it. Google created the KMZ file extension to allow your computer and Google Earth to easily identify and associate KMZ files with Google Earth. Otherwise, the operation would not be as automated in file associations.

SAMPLE / EXAMPLE SNAPSHOT OF A .KMZ FILE