As far as the distinction between an allegory and metaphor is worried, each seem to belong to exactly the same team of figures of speech. The rationale is always that each mean comparison. Se trata de un procedimiento ampliamente utilizado tanto en el lenguaje literario (sobre todo en la poesía), https://lukasuzbfg.suomiblog.com/the-2-minute-rule-for-metafora-50045453