Mozart's Symphony no. 40 in G minor vs Beethoven's Symphony no. 5 in C Minor.
According to Louise Cuyler who wrote the text called, "the Symphony", Second Edition (written in 1995) published by Harmonie Park Press from the University of Michigan,
"Mozart's G minor Symphony occupies a totally unique position in the whole oeuvre of Classical instrumental works. For many people, it stands as the consummate art work of the late eighteenth century; few would deny it a place among the supremely great compositions of all time. Assessing the source of its quality is difficult and probably not even desirable; but perfect balance among all its elements, the result of a great artist's intuitive knowledge of "when" and "how much," is one of this symphony's great treasures. Instruments are used with special magic, such a the initial entry of the wind choir, which stresses the first open cadence (first movement, meas. 14-20); or the lovely bassoon transition, commencing as this cadence concludes (meas. 20-22). All through the symphony, the horn parts are bewitching, especially if we consider that the natural horn had, at best, only eight or nine different notes.
'Mozart's knack for the dichotomy--for using musical elements in dualistic schemes--is more evident in the G minor Symphony than in any other of his works. It is conspicuous in his distribution of the orchestra; each choir is conceived of as an entity (occasionally several entities), and only rarely does the type of sound we call a 'mixture' develop. Even a casual glance at a few passages for full orchestra in the first movement illustrates this vividly; for example, measures 14-20, 34-42, 114-125. The strength of the dichotomy emerges also in Mozart's contrast of the diatonic passage with the chromatic. The two principal themes of the first movement illustrate this. Theme 1 is structured from the diatonic members of the key of G minor. Theme 2, on the other hand, is made lithe and insinuating by frequent infusion of chromatic tones, although it is strongly centered in B-flat, the relative major key.
An especially wonderful passage, contrasting the diatonic with the chromatic simultaneously, occurs in the final segment of the Restransition leading to the ...
This solution clearly assesses commonalities and differences between Mozart vs Beethoven. References are also provided to justify the assertions.