Google rolled out Maps Engine Lite almost a year and a half ago. Maps Engine Lite was a, you guessed it, lite version of the enterprise-level Maps Engine that let companies create custom maps for work purposes, then embed documents and media into the map and share it with multiple people. The lite version obviously didn't have all of the functionality of the business focused Maps Engine, but it was still a handy tool. Maps Engine Lite was a separate app from Google's My Maps service too, but that has changed today. Google has rolled Maps Engine Lite into My Maps, upgrading My Maps with some of the more robust Maps Engine features.
The updated service is still called My Maps, and keeps all of the Maps Engine Lite features. You can import documents and link them to a map, add custom photos and images, add icons, descriptions, and even embed YouTube videos right into your custom map. The upgraded My Maps also gets a new icon to go along with everything else. There's also some new exploration tools in the featured Google Maps Gallery. From the Google Maps blog: "As temperatures cool down, you might be searching for your next warm vacation spot. Starting today, you can get a little inspiration by going to Google Maps Gallery and browsing publicly shared custom maps of all types. Just look up sunny "Los Angeles" to find the best hiking trails, street art, breweries and more to do in La-La Land. And, for those of you who are actually looking forward to the winter, see what ski options others have recommended, with the maps they created of their favorite slopes and resorts."
If you have been using the older Maps Engine Lite service, all of your custom maps will be upgraded. You'll have the option to upgrade them yourself, but if you don't do it, it's going to happen automatically at some point. Google is just saying that the upgrade will happen before the end of the year. You might as well do it now and start playing with the added functionality in My Maps. You can find the new My Maps on the web, and the updated Android app is live on the Play Store.