Audsley and Irwin list Fife as a shrill open metal flute of 2' or 1' pitch. Wedgwood lists Fifre as a synonym for the Fifteenth or Twenty-Second, or a two-rank Mixture consisting of a 26th and a 29th. Only Audley lists all three names as synonyms, though he also lists Pfeife separately. According to Strony, the theatre organ Fife was extended from the Tibia Clausa or Concert Flute.
Osiris contains nine examples of Fife, all at 1' pitch except for one at 2' in a pedal division. That source contains only one example of Fifre (see below). No examples of Pfeife are known. Contributions welcome.