This paper introduces the topic of semantic distinctions between Spanish compound patterns (e.g., N+N, Adj+N). The semantic differences will be identified according to two parameters: the relationship between the extralinguistic entities and the compounds or their parts of them, and the semantic relationships inside the compounds. On the first topic, the argument structure of the compounds will be the key of the distinction, since the structure of V+N compounds is unchanging, whereas the one of N+V compounds is variable. More fine-grained differences will be identified from the point of view of thematic role assignment. On the second topic, the so-called "right-headed compounds" share a wide range of alternating semantic relationships, but the "left-headed compounds" show a unique semantic relationship. On the other hand, they show some distinctive features depending on the kind of noun classes that appear as their non-heads.