What are the groups of musical instruments? Are the terms “reed instruments” and “woodwind instruments” interchangeable? Or, is woodwind broader than reed? For example, what is a wood flute considered? And, is a metal flute a brass instrument?
Generally, the classifications are strings, woodwinds, brass, percussion, and voice.
Reeds are a subcategory of woodwinds, which further branch into single- and double-reeds. Saxophones are single-reeds, though their bodies are made of brass. In orchestras, the piano is a percussion instrument, though it has strings. (Actually, this is news to me – I didn’t realize there is no separate “keyboards” category. So where does that place the organ?)
Instrumentation for orchestral pieces usually runs flutes-oboes-clarinets-bassoons (woodwinds); horns-trumpets-trombones-tubas (brass); violins-2nd violins-violas-cellos-basses (strings); then specifies the odd percussion/harp/keyboards involved.
Subcategories (piccolos, Eb clarinets, contrabassoons, etc.) are listed after the instrumental categories.
Modern, metal flutes are still considered woodwinds.
Then you get into the tricky ones, like pianos. Are they percussion (the strings are struck by hammers, the keys are struck by the fingers) or string instruments?
Didn’t Earthling answer that one? You don’t tend to hear harpsichords in orchestras any more, but they would presumably be string rather than percussion.
Keyboards are listed among the percussion because the keyboards are laid out in the same fashion as xylophones and bells; if you can play one, you can play the other (hah).
There’s also bagpipes, which are a subclass of double-reeds.