Solid core doors are made entirely of solid material, typically wood or composite wood products like MDF (Medium Density Fiberboard). 

They offer better sound insulation and durability compared to hollow core doors. They are heavier and more substantial, providing a greater sense of solidity and quality.

Hollow core doors, on the other hand, have a hollow center that is usually filled with cardboard honeycomb or other lightweight materials. They are lighter, more affordable, and easier to install. However, they offer less sound insulation and are generally less durable than solid core doors.

In summary, the main differences between solid and hollow core doors are their construction materials, weight, sound insulation, durability, and cost. Solid core doors are heavier, more durable, and offer better sound insulation while hollow core doors are lighter, less expensive, and offer less sound insulation and durability.