Hood:
Armour: Belt: 12–6 in (305–152 mm)
Deck: 0.75–3 in (19–76 mm)
Barbettes: 12–5 in (305–127 mm)
Turrets: 15–11 in (381–279 mm)
Conning tower: 11–9 in (279–229 mm)
Bulkheads: 4–5 in (102–127 mm)
Renown:
Armour: Belt: 3–9 in (76–229 mm)
Decks: 1–5 in (25–127 mm)
Barbettes: 4–7 in (102–178 mm)
Gun turrets: 7–9 in (178–229 mm)
Conning tower: 10 in (254 mm)
Bulkheads: 3–4 in (76–102 mm)
So the belt is narrower, which I assume is what you mean. But don't forget that "even thinner" is kind of disingenuous - Hood's belt is heavier, but her deck is significantly lighter and it's the deck which killed her.
So you could say "due to her thinner belt armour" (which was battlecruiser grade, as compared to dreadnought battleship grade for Hood) or "overall worse armour" (which is debatable but broadly accurate at short to medium ranges) but "even thinner" is to imply that she's worse in the area which Hood had problems.
I was quoting a TV documentary, which said, "Renown was not allowed to engage Bismarck, because her armour was even thinner than Hood's." It didn't go into the finer points.