ATP synthesis with the F1/Fo ATP synthase enzyme is a method of synthesising ATP from ADP and Pi. In the Fo subunit of the synthase, there is a number of C rings - these differ between species.
Generally, animals have a lower number of C-ring subunits (around 8), due to their ability to maintain a more constant and steeper H+ gradient. In plants, higher numbers of C-ring subunits (up to 14) are required due to the variation in energy input (such as clouds and night interrupting sunlight).
Having a higher number of C-ring subunits reduces the need for a higher H+ gradient, akin to using a higher gear on a bicycle. Although this uses more protons to synthesise an ATP, it allows for ATP synthesis to continue when the transmembrane potential cannot be maintained to a high concentration (as occurs are night or during cloudy periods). This prevents the plant from dying prematurely, allowing the persistence of life.
As animal ATP synthases use fewer protons to produce the same number of ATPs (typically 8 H+ per 3 ATPs) than plants (typically 14 H+ per 3 ATPs), the synthesis is less efficient in plants. This is not an issue however, as plants have lower energy demands than animals - they are (generally) not mobile.