In reply to Pete Pozman:
I certainly used the term (e.g. in Scouting circles) 30+ years ago, so it isn't *new*.
To me going for a walk is a wander round the block or through a local park for an hour or so, whereas going for a hike involves putting your boots on, packing a rucksack and going to do something more serious probably taking all day or more, usually of a hillwalking type nature, though I'd not call a scramble a "hike".
We did have a joke in Manchester SSAGO (Uni Scout and Guide society) in the 90s that there were only two options, a "big hike" or a "little bimble"...
Post edited at 10:52