Looking at various particles regarding being fermions or bosons, it seems to me that fermions are something fundamentally different from bosons.
What I mean by "fundamentally different" is "as different as the electromagnetic force is to the strong nuclear force". The opposite, similar, is like "energy versus mass", or "photon particle versus wave".
Most notably, electrons, protons and neutrons are fermions, while photons are bosons.
Now, a difference that seems to me as fundamental as it gets is that the Pauli exclusion applies to fermions, but not to bosons.
On the other hand, there are very similar particles of which one is a fermion, and the other is a boson:
- A hydrogen ion - a single proton - is, as noted above, a fermion.
- A deuterium ion - a nucleus consisting of a proton and a neutron - is a boson.
To me, and to chemists, deuterium is just a hydrogen isotope, nothing special. Or in other words, they are fundamentally similar.
Now, are fermions and bosons fundamentally different, or "not really different"?
Maybe the cases above are in some way unsuitable to be compared to each other?