Assuming a teapot full of water has greater volume than a cup of water,
then the teapot of water can transfer more heat. In fact, the
definition of "heat" is the energy transferred from a hot body to a cold
body. The amount of heat depends on three factors: the mass of the
substances, the specific heat capacities of the substances and the
change in temperature. q=mcΔT. Since the other two factors are the
same, the greater mass of water in the teapot accounts for the greater
amount of heat.