How could s​ign convections of work done by the system and work done on the system be different in physics and chemistry

it's just a convention in physics we are more interested in getting some work output say a mechanical device , engine etc while in chemistry we are more concerned with the internal energy things so we do so in both the cases the result is same physics case : du = dq - dw , doing work on system increases ineternal energy as dw = negative for work donw on system and vice versa chem case : du = dq + dw ; doing work on system will increase the internal energy of the system as dw = positive which is obvious and vice versa we can take any sign convention in a given problem but we should be consistent with that throughout the problem to avoid confusion and mistake