No it isn’t. Particle board is not one product, first of all. It comes in all kinds of material compositions, densities, and coatings.

Yes, 3/4” sheet of MDF is heavier than plywood. Heavier than a panel made from construction wood species. Not necessarily heavier than hardwood.

But IKEA furniture is not made from MDF. The particle board they use is something far lighter and full of tiny voids where MDF has none.