As nouns the difference between headmistress and directress
is that headmistress is a female school principal while directress is a female director.
headmistress
English
Noun
(es)
(chiefly, British) A female school principal.
Synonyms
* headteacher (UK, gender-neutral)
* principal (US, gender-neutral)
directress
English
Noun
(directresses)
A female director.
Synonyms
* directrix