A Pratyeka Buddha is a 'hidden' Buddha who, however, does not start up a proper Sangha, or monastic community, for which salvation consists of waxing fat on a lazy doctrine while putting the squeeze on the laity for donations and forcing dalits to do the dirty work under conditions of more wretched yet social opprobium.
A Bodhisattva is not less than a Pratyeka Buddha- he has attained the prize- which is a phenomenal state- but he has a different intentional state- viz. he wishes to save other sentient beings by getting them to understand that the Jains and the Ajivikas and all other Sraman denominations- not to mention the Carvaka materialists- are totally fucked in the head and could everybody kindly be very very shitty to 'low caste' people- coz they don't got 'right livelihood-' and like immediately become a monk or hand us monks loads of money already?
Clearly, Pratyeka Buddhahood supervenes on Boddhisatvahood- in the sense that every Boddhisatva is indistinguishable from the stand-point of any Pratyeka specific measure- but the reverse is not the case. Two instances of Pratyeka Buddhahood can always be distinguished from the Boddhisatva perspective as approaching closer or standing in some relation to itself. (Either that, or Pratyekas are 'zombie' Buddhas and can't have 'real' intentionality.) But, why should this be?
One answer is that the Times weren't right for the Prayeka to set up a Sangha. In this case, there is some phenomenal state that supervenes- is multiply realizable across both Pratyekas and Boddhisatvas- but some 'cetana' or intentional state which does not similarly supervene. Why? Is it because sentient beings capable of Entanglement, as in the Avatamsaka or Vimalakirti 'Buddha field', do not exist? If so, something is added to the concept of Intentionality and something taken away from the scope of Phenomenology.
But Phenomenology does not disappear. The intention to be a Boddhisatva does not make you a Boddhisatva. You have to first instantiate in your phenomenal series that supervenient Pratyekadom otherwise you're just a wannabe.
Since, the Bodhhisatva 'cetana' or intentional state has supervenience- i.e. is multiply realizable- only if the ground for an entangled Buddhafield is ready at hand, an Occassionalist doctrine suggests itself as an (non) explanation for why the Pratyeka phenomenal state does not reduce to Bodhisattvadom.
In other words, Phenomenology and its dual Occassionalism re-appear in Buddhism as the two sides of the coin of 'Nothingness' which it cashes out as. Indeed, only the name of the coin changes, nothing sensible ever gets uttered, in this as in every other variety of peripatetic fraud or soteriological chicanery whose pious cultivation ensures we will always have more monks than reason.