I think "corpus" mainly appears in NLP area or application domain related to texts/documents, because of its meaning "a collection of written texts, esp. the entire works of a particular author or a body of writing on a particular subject." (https://www.google.com/search?q=define+corpus)
In contrast, dataset appears in every application domain --- a collection of any kind of data is a dataset.
Update: Please check this webpage , it is said that
"Corpus is a large collection of texts. It is a body of written or spoken material upon which a linguistic analysis is based. "