I've been using BCN Pro for a year, and BCN free for a couple years before that. I haven't used Gaia, so I can't say what the differences are for sure. There are two things that Gaia does that BCN doesn't do that I know of. The first is create routes that automatically follow roads (like Waze or Maps); instead, you need to create the route by clicking on all the major turns, creating a zigzag route instead of exactly following the road. It isn't a big deal, but the Gaia/ Maps way is easier. The other thing that BCN doesn't do is let you layer maps like Gaia. With Gaia, you can have Thunderforest as a base layer, then overlay the NFS Motor Vehicle Use Map (MVUM) to see what roads are open, and what you should stay off of, or you can layer a private lands map for the same reason. There are hints that this is possible in BCN (Hybrid maps), but I haven't figured it out. BCN can be difficult to figure out, but it is very powerful and does a lot of stuff. I feel like I am just scratching the surface with how I use it. The major difference is noticed by cheap people like me. Gaia costs $17 a year, while BCN Pro costs less than that for a lifetime. There is also BCNavXE; I don't know a lot about it, but it works on IOS and Android, and is what the developers have been working on the last few years (I don't think they are doing much more with BCNPro, although they say there will continue to be updates). Let me know If I can answer anything specific.
