In the case of what, I know that the Riserva (and now gran selezione) boil down to different ageing requirements.
Annata needs 12 months ageing and a minimum alcohol of 12%
Riserva is 24 months (minimum 3 months in bottle) and a minimum alcohol of 12.5%
Gran Selezione is 30 (again minimum 3 months in bottle) a minimum alcohol of 13% and also needs to be made from “estate grown grapes” and go before a panel to check it’s good enough (which I thought was supposed to be a requirement of all DOCG wine, but still).
[Edit: This is purely for Chianti Classico DOCG. For Chianti DOCG and the subzones there of the rules differ slightly, because of course they do]
The level of village/MGA-ification of Chianti (and bits of Piemonte) is a whole other kettle of mess. It will possibly be helpful in the long run, but there’s not enough information to help make choices, even in the regions I know well.
Burgundy: “Hey! I’m a hot mess of a classification system”
Northern Italy: “Hold my Roero Nebbiolo DOC!”
I know the theory is that producers put their better grapes in the higher up the pyramid wines. I can’t help but wonder if some use the extra age/oak to hide quality for fruit (I am looking at Rioja where I know this was very much the case a few years ago!).
So far I am getting, don’t try this one, but maybe don’t write off the whole category. I’m definitely not willing to spend that much on a wine that someone I know I have similar taste to thinks is a bit meh.