"mere difference" is correct and usable in written English.
You could use it to describe a situation where distinctions between two things or ideas are not significant or meaningful. For example, you could say "The two parties disagreed, but it was merely a difference in opinion."
That goes beyond a mere difference of tempo, it makes the piece a radically different musical and emotional entity.
This was no mere difference of opinion.
That makes mere difference, horizontal or otherwise, a hard thing to hang an identity on.
Considering the stakes, the immediate cause of this bitter argument seems a trifle: a mere difference of opinion on a matter of strategy.
Stripped of her or his national status, the stateless person of the 20th century is anathema because she or he presents difference – she called it the "dark background of mere difference" – to the world in its rawest, most debilitating state.
That distinction between how they interpret the intent of the voter standard is going to have a lot less effect on how votes are treated than the mere difference in the types of machines that are used.
The fact that Mariels and New Cubans continue to differ from Early Exiles and from one another in their remitting behavior suggests that there is something different about these two émigré cohorts that cannot be reduced to mere differences in sociodemographic composition or transnationalism factors.
This suggestion, together with Anaximenes' reduction of apparent qualitative differences in substances to mere differences of quantity, was highly influential in the development of scientific thought.
It may consist of (networks or patterns of) correlated data understood as mere differences or constraining affordances.
The shape of nanocrystalline building blocks greatly impacted on the fundamental electrochemical charge-storage mechanisms and, hence on the electrochromic response of these electrodes, due to concomitant bulk and surface-structure effects that could not be entirely traced to mere differences in surface-to-volume ratio.
Thus the representationalist seems to need an interpretation of representational sameness that goes beyond mere satisfaction conditions and reflects all the intentional or contentful aspects of representation without being sensitive to mere differences in underlying non-contentful features of the processes at the realization level.
