AK,
The Quantum Mechanical basis for the difference between bosons and fermions is that switching two identical bosons leaves the wave function unchanged while switching two identical fermions changes the sigh of the wave function.
When other properties of the state make such switching likely enough this property of the bosons adds to the likelihood of the combined state formed by having two bosons in the same state, because (1+1)^2 = 4 while 1^2+1^2 = 2. Having two fermions in the same state is forbidden, because (1-1)^2 = 0.
To have this enhancement for the bosons the two particles must be so closely in the same state that the effect adds up over the whole range, where the particles may move. Even slightly different momenta lead to incoherence, where the effect disappears.
In supeconductivity the situation is different, because the effective masses are very low. For that reason the coherence may be present even at relatively high temperatures. (The theory of superconducivity is rather complex. I haven’t gone trough it in full detail in spite of the fact that I have lectured from a book that spends much space for superconductivity, but that was many decades ago.)