Or Harry Roberts (I forget what book): A walk is a ramble through the woods on a pleasant day; a hike is 20 miles with a 20-pound pack and an M-16 at Parris Island.

Personally, I stopped worrying about the difference a long, long time ago. I suppose, if pressed, I'd say a hike is a group activity (yes, two is a "group") with a somewhat consensual common schedule, pace, and goal; a walk is just me, with a more nebulous goal and a schedule and pace that depend on my mood and the terrain. I'm also willing and able, on a moment's notice, to convert a hike into a walk by withdrawing my consent and leaving the group. So, I'd fall into the Fletcher way of thinking.