In this paper, we prove various inclusion relationships among different classes of algebraic structures and hyperstructures of type U on the right of finite size. In particular, we consider in detail the inclusion properties $$\mathcal{G}_n\subseteq \mathcal{PUR}_n\subseteq \mathcal{HUR}_n\subseteq \mathcal{SUR}_n$$ between the classes of groups $$\mathcal{G}_n$$, polygroups $$\mathcal{PUR}_n$$, hypergroups $$\mathcal{HUR}_n$$ and semihypergroups $$\mathcal{SUR}_n$$ of type U on the right of size n and provide conditions such that the equality holds. As a particular result, we prove that every polygroup of type U on the right is a group.
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