This tasting is of two nebbiolos blind, the only clue being “two wines from the same region“.
In theory
In theory, nebbiolo presents as pale coloured, full bodied, high in acid, high in tannins (very firm), high in alcohol, with potentially evocative attractive aromas and may be oaked or unoaked. Plausible laterals include sangiovese, nerello mascalese and sometimes pinot noir on the aroma (but not the palate).
In practice

The first wine presented as a high quality, balanced wine. It is a pale ruby in colour, with high acidity, very firm tannins, a full body, high alcohol (14.0), an evocative aroma (florals, red fruits) and is complemented by good quality oak. Whilst the aroma was a little Burgundian, the tannins, acid, body and alcohol, confirmed nebbiolo and a high quality example of it, likely from Barolo. This proved correct and the actual wine was the Rivetto Barolo Serralunga D’Alba 2017. I strayed a little on alcohol, noting the actual wine had 14.5 alcohol, compared to my estimate of 14.0. But this was consistent with my favourable assessment of its quality and balance. I would rate this wine as between very good and outstanding (★★★★☆).
The second wine was a smidgen lighter in colour than the first, and also a pale ruby in colour. The aroma was more red fruited, with no discernible oak, high in acid, high in tannins (sandy), full bodied and high in alcohol (14.5). This wine presented less distinctively than the first. The savoury, earthy red fruit aroma combined with high acidity and no new oak suggested Italy and nebbiolo but neither did it rule out Chianti. Chosing between these two, the key distinguishing features were that the wine’s tannins were a little firmer, and the fruit a little prettier, than sangiovese. Confirming evidence was the accompanying Barolo which could not have been anything else. The finish, balance and mid range quality supported this being a well made Langhe nebbiolo to be enjoyed for its savoury red fruits. The actual wine was the Marcarini Langhe Nebbiolo Lasarin 2020. This wine I would rate as “good” (★★★).
Tasted: March 2022.
