The simple answer is that there were many more Filipinos captured than Americans and the death rates were roughly proportional along the march (there were about 6 times as many Filipinos as there were Americans). Death rates afterwards in Camp O'Donnell approached roughly 30% for the Americans and roughly the same for Filipinos. With that being said, the simple (and unsatisfying) answer is that no one really knows exactly how many died, where, or how. All we can be relatively sure of is how many went in and how many came out. Many Filipinos slipped away during the chaos of the fall of Bataan, declining to follow the surrender orders, and even during the march itself to form guerrilla units during the war but many of those also didn't return - what their fate was, where they met their presumptive end, and how it occurred is lost to history, time, and the fog of war. For many, Bataan was their last known location and their lives ended either on the march itself, in Camp O'Donnell under unrecorded circumstances, or somewhere in an unrecorded guerrilla action prior the liberation of the Philippines. I'm sorry for the brevity of this answer and I'm happy to flesh it out further if there's something I can expand on. I also totally understand if this isn't in-depth enough to meet the stringent standards of the sub; to my knowledge, there's not a ton more to know about the March itself except for the details of the atrocities that occurred which have little bearing on who survived and who didn't because they were perpetrated almost without distinction on all the victims.

I think the subtext might be that there was a racial component to the casualty rates, that the Japanese were more brutal to the Filipinos than the Americans or less so to the Americans than the Filipinos. I haven't ever read anything to indicate that was the case and, in fact, I have read about the Japanese attempts throughout the 1930's to form closer cultural ties with the Philippines (largely for pragmatic reasons, attempting to supplant American influence). In fact, the Japanese formed an armed Filipino contingent during the war that was nominally equal to the Japanese Army, the Makapili, that largely fought guerrillas; participation was dwarfed by Filipinos who fought against the Japanese (hundreds of thousands fought against versus thousands who fought for them).

I can come back in a little while and flesh this out a bit more with some info about the Japanese interaction with the Philippines during their occupation and perhaps a bit more about Japanese racial attitudes toward the Filipinos.

Edit: that took a little longer than I thought. In regard to racial theory in Japan, there's an odd mix of multiculturalism and racial hierarchies to justify colonialism. On the one hand., claiming a shared Asiatic heritage lent credence to the claim that the Japanese should lead a pan-Asian sphere of influence. On the other hand, the Japanese considered (arguably still consider) themselves a pure race linked by blood with the Emperor and their inherent racial superiority to justify their colonial occupations. At a 1931 conference on inter-marriage in colonial areas they ultimately concluded that there'd be no weakening of the bloodlines as long as "extreme crosses" were avoided like "White and Aboriginal" or "Asiatic and Negrito". Views muddled throughout the 1930's, partially driven by an embrace of Nazi racial theories as the countries grew closer but also distanced from them as the Nazis rejected the Japanese as full equals. The result was a sort of disjointed racial theory in which the Japanese acknowledged that no race was pure but maintained that their race had unified around an identifiable, and superior, set of characteristics. They made racial distinctions down to a regional level as well (some Koreans, for instance, were "better" than others). I'd have to do more digging to find out whether they ever reached an intermarriage policy but they definitely had it on the list of things that needed to be completed to administer their eventual empire (as well as studying whether the Japanese race could thrive in their new dominions).

In the Philippines, they established a puppet state, permitted Tagalog as the official language, and encouraged both Japanese and Filipino cultural practices. They also massacred 150,000 or more Filipinos and allowed hundreds of thousands more to die in war-related famines; of the more than half a million Filipinos who died during World War 2, less than 30,000 were military dead. Their actions during the Manila Massacre systematically destroyed a major cultural site and annihilated its population. There's no way to possibly frame their actions in the Philippines throughout the war as anything less than brutal and there were at least 70 incidents of war crimes. This is even more remarkable when you consider that the Filipino resistance was very active, so much so that the Japanese occupation forces only controlled a small portion of the country and that in some areas the Filipino resistance operated openly as the government. It's worth noting that the Philippines were the second wealthiest nation in Asia before the Japanese invaded.

I realize this has digressed substantially from the narrower scope of the original question but I think it's important that events that are very temporally limited are placed in some part of the context in which they occurred in order to understand perhaps why they happened the way they did. Ping me with questions if you'd like, I'm on the road a bit today but will try to jump back in to answer.