This note is to refute Bejan's accusation (Bejan, 1983) that our work on field synergy (Guo, 1998) is a duplication of his idea of "heatline" (Kimura and Bejan, 1983), however in fact the two are significantly different. The former treats the convective heat transfer as heat conduction with heat sources which are the dot product of local velocity and temperature gradient, whereas the latter regards convective heat transfer as a flow of net energy which is simple combination between heat flow and enthalpy flow, and introduces a heat function borrowed from the streaming function in fluid mechanics,. The use and robustness of the two are also different. The field synergy is useful in enhancement/optimization of convective heat transfer, but heatline theory is only for visualization of convective heat transfer. (C) 2015 Elsevier Ltd. All rights reserved.