Electric field intensity is the strength of an electric field at a given point, and an equipotential surface is a surface where the electric potential is the same at every point :
Electric field intensity : The force of the electric field at a given point, measured in volts per meter or newtons per coulomb. It's equal to the electric force per unit charge experienced by a test charge placed at that point.
Equipotential surface : A surface where the electric potential is the same at every point. The electric field is always perpendicular to an equipotential surface. The work done in moving a charge between two points on an equipotential surface is zero.
Equipotential surfaces can be planes, solids, or other shapes, but they can't be point-sized. For example, the equipotential surfaces for an isolated point charge are concentric spheres, and the equipotential surface for a line charge is cylindrical.