From the middle-late decades of the last century, many researchers such as Bennett, Benoif, Deutsch, Feynman, Manin, Wiesner, among others, had some intuition that qubits are computationally more powerful or more interesting than classical bits.
Physically embodied qubits as we understand and intuit nowadays are fundamentally distinguishable "particles" or "atoms". For example, at a high level we need to separate and index the wires in our circuit diagrams, but also more concretely we can point to individual ions in a trap or individual transmons and identify and label them as separate and distinguished.
But, quantum mechanics is also concerned with two classes of indistinguishable particles - namely fermions and bosons.
Going back all the way to the 1920's, Jordan and Wigner provided a mapping between the wavefunction in a Hilbert space spanned by a number of qubits and the wavefunction in a Fock space spanned by fermions. Feynman also hinted that a qubit could be defined by the presence or absence of such a particle. But, for fermions at least the sign problem is a separate issue that needs to be carefully addressed - e.g. whenever two fermions are swapped, the wavefunction picks up a negative phase.
Furthermore regarding bosons, Aaronson and Arkhipov noted that sampling bosons such as photons from a network of mirrors and beam splitters is related to calculation of the permanent, while sampling the same for fermions is related to the determinant. It follows from Valiant's theorem that boson sampling is likely much (much) more difficult than fermion sampling.
On the one hand we have fermions, which naively have the sign problem making simulation more difficult; however, fermion sampling is in P. On the other hand boson sampling is most likely not in P - nor is it likely to contain P.
But, can we translate between fermions, bosons, and qubits efficiently? For example could we have created a quantum computer out of indistinguishable bosons instead of distinguishable qubits?
Because of the Pauli exclusion principle, a chain can be either occupied or not with precisely one fermion, while bosonic occupancy is unlimited. BosonSampling experiments try to mitigate this by having at least quadratically more modes than bosons.