Britishism vs formulation

Britishism and formulation both are nouns.

Word	Noun	Adjective	Verb	Adverb
Britishism	Yes	No	No	No
formulation	Yes	No	No	No

As nouns, formulation is a hypernym of Britishism; that is, formulation is a word with a broader meaning than Britishism:

Britishism: an expression that is used in Great Britain (especially as contrasted with American English)
formulation: the style of expressing yourself

Other hypernyms of Britishism include expression.

Britishism (noun)	formulation (noun)
a custom that is peculiar to England or its citizens	inventing or contriving an idea or explanation and formulating it mentally
an expression that is used in Great Britain (especially as contrasted with American English)	the style of expressing yourself
	a substance prepared according to a formula