Diatype is a term first used by the linguist Michael Gregory to describe a type of language variation which is determined by it's social purpose. In his formulation, language variation can be divided into two categories: dialect, for variation according to user (eg. African American Vernacular English), and diatype for variation according to use (eg. the specialised langauge of an academic journal). A dialect (from the Greek word διάλεκτος) is a variety of a language used by people from a particular geographic area. ... African American Vernacular English (AAVE), also called Ebonics, Black English, Black Vernacular or Black English Vernacular, is a dialect and ethnolect of American English. ...

The distinction between the terms is not always clear; in some cases a language variety may be understood as both a dialect and a diatype. The term register is often used in place of 'diatype'. The terms style and genre can also overlap in meaning. John Swales presents six defining characteristics of a discourse community in his text Genre Analysis: English in Academic and Research Settings (1990). ... Speech community is a concept in sociolinguistics that describes a more or less discrete group of people who use language in a unique and mutually accepted way among themselves. ... Historically, a register was a sign or chalkboard onto which people would write cash transactions for later bookkeeping, often with chalk. ... Style may refer to genre, design, format, or appearance, including: Clothing: fashion Flower part: flower Music: music genre Sundial part: Gnomon Titles or honorifics: Style (manner of address) including Chinese courtesy names Web design: Cascading Style Sheets Writing: style guide and literary genre Linguistics: Variation in language use of an... A genre is any of the traditional divisions of art forms from a single field of activity into various kinds according to criteria particular to that form. ...

Three variables of dialect are:

• Geographical: Where the speech community is based.
• Social: What social group/s the speech community belong to.
• Temporal: In what time (present or historical) the speech community exists.

Diatype is usually analysed in terms of: Speech community is a concept in sociolinguistics that describes a more or less discrete group of people who use language in a unique and mutually accepted way among themselves. ...

• Field: The subject matter or setting.  
• Tenor: The participants and their relationships.
• Mode: The channel of communication, such as spoken, written or signed.

References

• Gregory, M. (1967): Aspects of Varieties Differentiation, in: Journal of Linguistics 3, pp. 177-197.