"trekking" is for the sudo-intelectuall know nothings that want
to impress you with their fancy pants chrome bits. they're
often seen touri....err...trekking...on their "fi-shays."

"touring" is for regular joe-six-packs who load up some gear
on a bicycle and go ride.

it's much like the two types you find on travel/tourism forums;

you got your reg'lar folks who go on vacation and are content
with the designation "tourist."

then of course you have the eco-crunchy rainbow warrior
quiche-eating, free-range tattoo, stinky dreadlocks, oversize
cut-off-with-scissors, no shoes, che gavuera t-shirt, mao ze dong
messenger bag, save the planet, blahblahblah, who insist
you call them "travellers."