Although there are some differences of opinions as to how different types of metaphors ought to be classified, there seems to be agreement among the majority of linguists on the nature of correlation between metonymy and metaphor. Already at the very beginning of 1980s, Lakoff and Johnson started to describe similarities between the two cognitive phenomena. They thought that metonymies, similarly to metaphors, are not arbitrary linguistic phenomena, but that their systematic occurrence suggests that they are “part of the ordinary, everyday way we think and act as well as talk” (Lakoff and Johnson, 1980:37). Moreover, they claim that metonymy is even more basic to human understanding than metaphor, since metonymies most frequently involve direct physical or casual associations.
However, there are also some differences between the two. Namely, metaphors involve mapping between two different conceptual domains, while metonymies allow one entity to stand for the other because both of them exist within the same domain. Additionally, the fact that in metaphors the logic and structure are mapped from source domain to target domain suggests that metaphors are used mainly to ease understanding of certain concepts while metonymies are used for reference. Therefore, since metaphorical expressions are used to explicate complex or abstract ideas, they are more elaborated than metonymies which are oftentimes used in speech as a sort of cognitive and linguistic shortcut. What is more, as Mendoza Ibáñez suggests “the relationship between the source domain and target of a metaphor is of the “is – a” kind; in metonymies there is a “stand – for” relationship” (Ruiz de Mendoza Ibáñez, 1998:113).
The differences between the nature of metaphor and metonymy might be illustrated by the following graph (Evans, Green, 2006:313):
Although the differences between metaphors and metonymies seem clearly visible in structure and usage, in fact, it is frequently extremely difficult to definitively state whether a given phrase is metaphorical in nature, or metonymic. Detailed analysis of the manner in which metaphors and metonymies interact led Goosens to the conclusion that there are at least a few possible ways for such interactions, however, he also concluded that only two of these can be commonly found. Goosens coined a new term to denote such an interaction – he named it “metaphtonymy”. He called the first commonly experienced relation metaphor from metonymy as in this interaction the metaphor is grounded in a metonymic relationship, and the second interaction was called metonymy within metaphor (Evans, Green, 2006:320).