I'm stuck thinking that Both are similar and thus equivalent. Am I wrong?
The eating of your own species is rare in the animal kingdom. Some spider females https://en.m.wikipedia.org/wiki/Spider_cannibalism kill and eat their partner after copulation. Ants eat other ants. Scavengers would also eat anything they can get their ‘hands’ on. But mammals killing their own species for eating is rare. Lions kill the cubs of other lions but not for food. Chimps are able to kill other Chimps. Humans have a neocortex that is overdevelopped compared to other species and one would think that being able to feel empathy would help prevent cannibalism. But humans have not survived on astronaut food for millennia. Most animals need other life forms to nurture themselves and even some plants have specialised in attracting animals to ‘consume’ them. But eating your own species comes close to self-eradication. Also eating another human could have other humans want to kill (and Maybe eat) you. So only in communities where strict agreements about which people could possibly be on the menu without retribution cannibalism could work, most probably supported by a scapegoat mechanism where the anger of a group could be focused on the victim or could be pacified by the flow of blood.
In the wild suicide is not an evolutionary asset and cannibalism could be expected to die out, the more we turned ‘civilized’. That is why cannibalism differs from eating other life forms.
A quick Google search or look onto Wikipedia will reveal that cannibalism has not been universally banished by society, and there are advanced societies (such as the pyramid-building Aztecs) that practiced cannibalism.
Jewish law would not have allowed cannibalism for several legal reasons, including the ban on murder, the requirement that animals eaten as meat be slaughtered in a specific and humane way, and the ban on eating creatures that were found dead.
In western society, I suppose that cannibalism has never been accepted for similar reasons, i.e. that it would always entail either murder or unsafe meat-handling practices.
Also, people generally recoil at dead bodies, so it is unlikely for human meat to be appetizing.
No answer considered this from the most important perspective: the biological one.
In the case of humans, due to the existence of PrPc (cellular prion protein) the presence of proteinacious infectious particles can influence other similar healthy proteins and change them, causing a chain reaction of infection and creating disease (the pathogen causes transmissible spongiform encephalopathies / TSEs). Specifically, TSEs disease creates holes in the brain, giving it a spongi-looks and causing degradation which ultimately causes death. This cannot be countered with heat (natural organic defense) or even with radiation.
That aside, from a general perspective, eating the flesh of the same species is in most cased extremely inefficient and. Basically the whole organism can fail to process it properly because it can consider it part of itself.
From a philosophical perspective, everything depends on the culture we consider. Cannibalism was practiced in parts of the Solomon Islands, Fiji Amazon Basin, Congo NZ (Māori tribes) and flesh markets existed in some parts of Melanesia.
In Papua New Guinea it's still practiced today (cultural reasons). So it's a matter of culture too.