Entropy of electricity and heat

Entropy change potentially consists of two components: entropy transferred plus entropy generated. Only heat transfers entropy. Work (including electrical work) does not transfer entropy. On the other hand both heat and work, if irreversible, generates entropy.

For the energy transfer to be reversible, the rate of energy transfer must be very low (power approaching zero). The rate of energy transfer in your examples (1 MJ/s) certainly does not approach zero. So both processes are irreversible and generate entropy.

However, since only heat transfers entropy and work does not, one would expect that the total entropy change due to irreversible electrical work would be less than the total entropy change for irreversible heat transfer, for the same amount of energy transfer (3.6 GJ).

Hope this helps.