Hence why I'm asking about embryos. What, scientifically, differentiates a human embryo from a mouse embryo, beside what it may eventually become? Why find the

Hence why I'm asking about embryos. What, scientifically, differentiates a human embryo from a mouse embryo, beside what it may eventually become? Why find the experimentation of one appalling, but not the other, when neither is allowed to grow? (I am not arguing one way or the other, merely that it is illogical and unscientific to differentiate.)