Crown Willow, Pro Willow, Test Grade Willow ...
There could be some truth to it but I personally think it's mostly a marketing gimmick to rob your wallets.
It's the same Willow Trees. Those trees have not suddenly started to produce some extra special kind of timber, or did they?
Every other year, a new "willow term" is created, some new stickers are put on the bats and price is hijacked. Some new "over drying" tricks are developed to make the bats look bigger and fatter in regular weight.
Newbury got a bat for £1000.00, GN got one for £850, PUMA and KOOK got it for £850 - I mean, what the heck? Are these coming from some new genetically modified trees?
This is the same quality of willow that was marketed for less money a few years ago under the tag of Grade 1, then grade 1+, then grade 1++ etc. A now it's "Pro Willow" for 5 times more of the price.