However, we can talk generally about what a 0.2-liter difference *could* mean:
* Bore and Stroke Changes: The most likely explanation is a slight increase in either the bore (diameter of the cylinders) or the stroke (distance the piston travels) of the 7.5L engine compared to the 7.3L. Even small adjustments to these dimensions can significantly impact displacement. This might be done to increase power output, torque, or improve fuel efficiency, although it might also be a side effect of other design changes.
* Different Engine Families: It's entirely possible these numbers refer to entirely different engine designs from different manufacturers. A 7.3L engine from one company might have very little in common (other than displacement being in the same general range) with a 7.5L engine from another.
* Rounding/Marketing: It's also possible that the difference is smaller than the numbers suggest. Engine displacement numbers are often rounded for marketing or simplicity. A 7.28L engine might be advertised as a 7.3L, and a 7.49L engine as a 7.5L.
In short: Without knowing the specific manufacturers and models of the 7.3L and 7.5L engines you're comparing, it's impossible to say definitively what the difference is. You'd need to look at the engine specifications from the manufacturers.
