Both varieties fruit on new growth which pops out of last-year’s canes. With Perlette, which should be “spur pruned” (shorter pruning of this year’s wood), the fruit clusters will form closer to the main trunk. With the Thompson, which is “cane pruned”, a bit more of this year’s wood is left and clusters of fruit form farther towards the tip of where you prune. Here’s a good writeup. And!! It mentions both varieties.
I can never remember this stuff, so refer to reference books or bookmarked web pages. Kiwis get similar treatment. Fungus is a big issue over here; so I stopped growing grapes some years back. Hardy kiwi are much easier to grow here, but I’ve neglected the old vines and they need “chainsaw correction”!
