DrumStaff vs Staff for instrument name

[Menu Jacques]

Hello folks,

In the example below, using Staff.instrumentName makes no difference compared 
to DrumStaff.instrumentName.

Are both equivalent, or should DrumStaff.instrumentName clearly be preferred?

Thanks for your help!

JM

—

\version "2.19"


P_PTwo_Staff_One_Voice_One = \relative {
  \key c \major
  \numericTimeSignature \time 4/4
  \clef "percussion"
  \once \override NoteHead #'style = #'cross 2. \once \override NoteHead 
#'style = #'cross 4 | % 2
  \once \override NoteHead #'style = #'cross 1 \bar "|." |
}

\score {
  <<
        \new DrumStaff = "P_PTwo_Staff_One" <<
          \set Staff.instrumentName = "Cymbals"
          \context DrumVoice = "P_PTwo_Staff_One_Voice_One" <<
            \P_PTwo_Staff_One_Voice_One
          >>
        >>

        \new DrumStaff = "P_PTwo_Staff_One" <<
          \set DrumStaff.instrumentName = "Cymbals"
          \context DrumVoice = "P_PTwo_Staff_One_Voice_One" <<
            \P_PTwo_Staff_One_Voice_One
          >>
        >>
  >>

  \layout {
  }

}