1. What is a vertex of a solid object ?

vertex usually refers to a corner of a solid such as a cuboid.

2. What is the difference between a cube and a cuboid?

cube has all of its sides equal. A cuboid can have sides of three different lengths.

Typical examples would be:

Cube − a sugar cube
Cuboid − a shoe box

3. What is the difference between a cuboid and a prism?

prism is a solid object with the same shape or cross-section all the way through.The cross-section can be any shape e.g. A triangle or a circle.

cuboid is a prism with a rectangular cross-section. e.g. A cardboard box at the supermarket.