Given, mass of both disc is same.

m₁= m₂ =m

and, thickness of the discs also same,

So, t₁=t₂=t

But the materials of discs are different,that means the densities of both materials are different.

Let the density of first disc material is =Ρ₁

and  density of second disc material is =Ρ₂

So, Ρ₁= mass₁ /volume₁ 

and Ρ₂ = mass₂ /volume₂      (m₁=m₂= m)

so,  Ρ₁V₁ = Ρ₂V₂

= (π.(r₁) ²).t×Ρ₁ = (π.(r₂)²).t×Ρ₂

r₁ and r₂ are radius of discs.

Ρ₁ /Ρ₂ =(r₂) ²  / (r₁) ²

Moment of intertia of circular disc is-

I = (1/2)mr²

So, I₁ /I₂ = 1/2 m(r₁)² / 1/2m(r₂)²

= I₁ /I₂   =(r₁) ²  / (r₂) ²   = Ρ₂ /Ρ₁

So, the moment of inertia will depend on the radius of discs and density of the materials.