Google Maps is free and allows the user to choose from a variety of basemaps, upload files, and draw features onto the map.
Google Maps Engine
Google Maps Engine is similar to Google Maps but it has more capabilities and is not free. Google Maps Engine can support a wider variety of file uploads, more complex maps and has more sharing options.
Google Earth Pro
Google Earth Pro is the paid version of Google Earth. Unlike Google Maps and Engine it uses high quality satellite imagery and 3D imagery. The user can create maps, model new buildings, and create a video of 3D imagery.
Google Earth Tourbuilder
Google Earth Tourbuilder is free and uses Google Earth imagery to allow the user to create a tour.
Google Crisis Response
Google Crisis Response responds mainly to natural disasters. Often Google Crisis Response will have a resource page and host a crisis map with information from authorities and the crowd. Google Crisis Response also has a variety of products for responders.