Quantum mechanics focuses more on probability and specific units which seems more empirical. Whereas relativity is more theoretical and thus rationalist.
In my opinion, there is a degree of mysticism in quantum mechanics because it is not properly formulated. It is generally recognized that ψ.ψ* represents the probability of finding the particle at a specified set of coordinates (the Born rule) but this has to be wrong. Consider a particle moving from A to B in accord with the Schrödinger equation. According to the Born rule, the most probable place to find the particle is at the wave antinode, but that cann0ot be correct because if you do the mathematics, the wave travels at half the velocity of the particle. The particle is at a pace where the wave has yet to catch up.
Now you can wave your arms and say the wave doesn't exist an dit is just a calculating aid, but even if that were true, if the most obvious simple calculation gives the wrong answer, how can it be a calculating aid?
There is a lot more wrong with current quantum mechanics, in my opinion. As an example, besides the Born rule two other Nobel prizes have been awarded with, in my opinion, incorrect physics. The award to Pople for his calculation of chemical bond energies uses the wrong orbitals and misses a quantum effect. The difference between what he uses and what I believe should be used is not large and is compensated for by assigned constants, i.e an empirical correction. The orbitals he should use are given by the relationship in I. J. Miller 1987. The quantization of the screening constant. Aust. J. Phys. 40 : 329 -346. As it happens, the carbon p orbitals do not have radial nodes, and the 2s orbital has only a minor effect so all is not lost
Similarly, the 2022mprize for showing violations of Bell's inequality is wrong. All they did was in calculating the results, they violated the conditions of deriving the inequality. If you do not believe me, show where the error is in Miller, I. J. (2023). Non-Violations in Bell's Inequality. J Math Techniques Comput Math, 2(6), 209-210.
I concede to being biased since I have published papers contradicting standard QM and In have also written two ebooks, one is "Guidance Waves", which outlines my answer to what I think is more correct, and "The Covalent Bond from Guidance Waves", which accounts for chemical bonds. The sim0lifications are clear. As an example, the calculations of bond dissociation energies for then triply bonded P2, As2 and Sb2 are within about 2 kJ/mol with no assigned constants, and a computer is not needed for what is one analytic function that inserts different quantum numbers.