Good question!
Yes, because it is very easy to get confused: we are dealing with two wines that have in common their typology (white wines) and their country of origin (France) )…and then? That’s it!, or rather “c’est tout!”. Yes, because:

Pouilly Fuissé is produced in Burgundy, specifically in the Maçonnais region, and is Chardonnay-based.
Pouilly Fumé is produced in the Loire Valley, AOC of 7 communes (Garchy, Mesves-sur-Loire, Pouilly-sur-Loire, de Saint-Andelain, Saint-Laurent-l’Abbaye, Saint-Martin-sur-Nohain and Tracy -sur-Loire), and is based on Sauvignon Blanc.

So different for grape variety, terroir and therefore for organoleptic profiles. But I’ll tell you more about this in my next tastings!