The software interface you see on the Android app viewing Navionics charts is -- of course -- much different than the interface on the chart plotter. So even the way you interact with the chart changes a bit: on the Android app (or iPhone / iPad with iNavX app) you may find zooming and panning around a chart more effortless and fluid. And you may tend more often to query the data "cooked" into the Navonics chart in terms of finding out details on a given buoy or other navigation related object. By the way, some of the apps out there actually have higher definition charts compared to, say, Navionics Gold cards.

Another thing worth mentioning is that physical Navionics SD and CF cards are not locked to just a particular Android or iOS app. As another poster mentioned, the charts on the card aren't really "downloaded" to a chart plotter, the plotter just reads the card contents on demand; and many chart plotter models may be compatible with a given card. Even better, you can use Windows PC software like Navionics NavPlanner 2 (Google that) to read and cache to the hard drive all the contents of the Navionics cards that have come out in the last 2 years. So in some ways, the Navionics cards have more flexibility than mobile app + chart purchases. Depends on your needs and the price points; email [email protected] if you have any questions about Navionics cards or downloadable charts.