That is a harder question to answer. Some games have more post-processing/over-sampling than others and some GPU's will handle one better than the other. We have numbers for resolution...
1920x1080p = 2,073,600 pixels rendered per second
2560x1440p = 3,686,400 pixels rendered per second
Just moving to 1440p using same in game settings will ask the GPU to work significantly harder. Without numbers to associate in-game settings with workload of the GPU, it gets difficult to say which would be more taxing on the hardware but one thing can be said for certain, more or higher resolution means even more VRAM you will need for post-processing\effects