HERE 360, the official blog for HERE Maps, published a chart comparing its offline service to Google Maps. First, the comparison shows offline support for both platforms. HERE won by a long shot offering offline driving, transit, and walking directions while Google Maps was only able to give one route of driving directions while offline. Being in New York City, one can appreciate when a maps app offers public transit directions. HERE claims you can get transit directions when offline. I was NOT able to do this on my Nexus 6P (gave me a "no transit route found" error). I was finally able to pull up transit direction offline with an iPhone 5S, but it must have taken 30 seconds for the app to figure it out. HERE lets you download offline maps by state but Google Maps will only let you download one selected area at a time. This is not ideal for, say, a road trip where coverage is spotty. Even though you can download these areas in Google Maps, HERE makes a point that "you can download the entire state of California for less than 540MB. Google Maps needs about the same amount of space for just part of Northern California.". Countries that perhaps don't have good mobile coverage should use HERE Maps for much better offline navigation. HERE definitely offers a competitive package worthy of competing with Google Maps. At Google I/O this year, Google promised full offline Maps by the end of the year. Soon, HERE maps will have much more to compete...
Source: http://www.gsmarena.com/here_maps_compares_itself_to_google_maps-news-15081.php