Some more examples; I, as a moral actor, am able to foresee the consequences of my actions, because I understand the difference between right and wrong. So if I steal something, I know that I'm depriving someone else of that item, which in this instance is wrong, and I know that I can be held accountable for my actions on the basis that I know the act I'm committing is wrong. On the other hand, when my cat Jasper walked in carrying a joint of pork, there was no point in doing anything (other than cutting the joint up and getting the cats to dispose of the evidence) because he couldn't understand the consequences of his actions for others, and he couldn't understand the distinction between right and wrong; which is why he falls under the category of moral patient.
Here's another example; I can consent to work because I can weigh the potential disadvantages of the job against the potential rewards of doing that job, but in law we recognise that a child can't—she might not appreciate that regardless of how many lollipops she gets, cleaning out a nuclear reactor has implications for her health, as an extreme example—which is why (well, part of the reason) we have legal restraints on the hours and conditions of children's employment.
So a moral patient is someone who is unable to manage their rights, and therefore needs to have someone who is morally capable to manage their rights for them (this is the point of making such a distinction). A moral patient deserves no less consideration than a moral actor, and maybe even more so, because of the complexities of appointing someone as a guardian for that person; for instance, to ensure that the appointed guardian is actually acting in the best interests of their ward, and not using their ward to further their own interests.