Navico is the parent company of C-Map, B&G, Simrad, and Lowrance. The devices are more or less the same across product lines, each geared to a separate market, B&G for Sailors, Simrad for power boats and cruisers, and Lowrance for fishing.
Navionics bought C-Map from Jeppsen a few years ago. Jeppsen was/is a major mapping firm that specialized in Aeronautical charts.
Navionics and C-Map use the same data, except for the crowd sourcing. The features are pretty much the same.
I have both Navionics and C-Map and tend to use the C-Map charts on my chartplotter. Navico has been investing in C-Map and this year have simplified their chart selection. They have also integrated a free web based charting app, and a free tablet/phone app with a subscription option to allow charts to be downloaded. I have a B&G Zeus2 CP and the three features play nice together. I can plot courses and waypoints on the 27" computer screen and they are downloaded to the iPad and the Zeus automatically. The Zeus needs to be connected to the internet via wifi or a hard wire connection.
Navionics is more mature than C-Map, in that it has been around longer so there are more people who are familiar with it, and subsequently more people will recommend it. My preference with electronics is to stay within one system, whether it is on the boat or home because staying within one ecosystem reduces the chance of something not working and you get better tech support, no one ever says "its not our problem, it the other guy's problem, call him up."
C-Map offers the most personal, stress-free, end to end marine experience by providing high-quality nautical maps along with navigation, traffic and weather information to easily plan trips on the water and enjoyable experience with peace of mind.
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