A lot fewer features, a lot more streamlined UI. OSMAnd has too many features for my needs, it takes longer to figure out how to do something. I think a lot of people agree. But maybe OSMAnd works better for you.

OsmAnd: tons of customization options, "prefer unpaved roads" routing option (great for adv motorcycling), can follow GPX tracks, battery hog.

Organic Maps: quick, minimalistic UI, can display but not navigate along GPX tracks. Lighter on battery. I use it like I would use paper map when hiking.

Anecdotally, I've found OSMand's search functionality to vary between OK and completely unusable. Especially when entering addresses, OSMand really struggles to interpret what should be quite straightforward entries.

While I haven't extensively used OrganicMaps, I found its search functionality to behave much better.

I use OSMAnd on my phone, where the extra features are useful for hiking and biking. I use Organic Maps on my iPad where I want a simple offline map.

I haven't used OSMAnd, but I'd give it a shot. What's up with the $30 premium version on the Play store?

In my opinion OSMAnd interface is slow, that of Organic is very responsive