What is the main difference between Thermo Dynamics and Heat Transfer ?

Thermodynamics is the study of a system with respect to its thermal energy. It can be used to describe the state of a system in terms of temperature, enthalpy, entropy etc, just as the same way as one can describe the system with respect to its magnetic properties like magnetic nature, susceptibility or electrical properties like capacitance, resistance or inductance etc.
heat transfer is much different and simple to understand. Heat is the energy of transference which arises due to temperature difference between two bodies. It doesn't need any other factors like pressure, internal energy etc.