What is the difference between the molecular geometries of tetrahedral and trigonal pyramidal structures?

The main difference between the molecular geometries of tetrahedral and trigonal pyramidal structures is the arrangement of atoms around the central atom. In a tetrahedral structure, there are four atoms or groups of atoms arranged symmetrically around the central atom, forming a shape like a pyramid with a triangular base. In a trigonal pyramidal structure, there are three atoms or groups of atoms arranged in a triangular shape around the central atom, with a lone pair of electrons occupying the fourth position, giving it a pyramid-like shape with a triangular base.