Is there a difference between a gravel bike and an adventure bike?
My interpretation is thus;
-Gravel would mean tyre clearance for 40c as suggested and more relaxed geometry than a road bike, lower BB.
-Adventure would mean the above, maybe tyre clearance for up to 2″ tyres on 650b, loads of points for mounting bottle cages, etc., and perhaps even more relaxed geometry than a gravel bike for more stability when carrying luggage on rougher terrain.
I wince whenever (and it happens regularly) when someone asks about ‘gravel’ and/or ‘adventure’ bike and several people immediately recommend the cyclocross bike they have; they are designed for riding around a muddy field for a couple of hours on tyres around the 32c mark. I’ve gone from a CAADX to a Sequoia so am talking from experience though do acknowledge there is some overlap.