Properly speaking, in English usage if it's a Pianola (capital letter)
then it's Aeolian trade name.  If it's pianola (no capital letter) it's
a generic description.  Other languages vary in this use of capitals,
of course.

Aeolian did not invent the Pianola, the name or the instrument.  This
honour belongs to Edwin Votey: the first few hundred Pianolas were
manufactured by the Votey Organ Company, soon snapped up for the
expanding Aeolian empire, followed a year or so later by its inventor
(who, of course, went on to invent the Duo-Art).

The name Pianola went generic very quickly.  Gustav Kobbe wrote his
book, "The Pianolist", in 1907 and decided to use the term in its
generic sense, and justified doing so in the first chapter, "The title
and purpose of this book".  As he wrote,

  "I confess that before I started this paragraph I was puzzled to
  know what term to use in designating the instrument I had in mind.
  "Mechanical piano-player" is a designation which not only does
  not appeal to me, but, furthermore, fails to do justice to the
  instrument, which, although mechanical in its working, is far from
  being mechanical in its effects.

  "The result? -- I took a cross-cut and arrived straight at the word
  Pianola as being the name of the most widely known piano-player, and
  happily derived from the name of the most widely known instrument,
  the piano.  For this reason the term Pianola was used in the
  paragraph referred to and now is employed in this book; and, for the
  same reason, this book is called "The Pianolist".  It is believed to
  be the title least requiring explanation, if, indeed, it requires any
  explanation at all.  Right here, however, I must add that the company
  which manufactures the Pianola objects to the use of the word as a
  generic term."

You can check the progress of these things by means of old dictionaries,
and in England the term pianola was regarded as generic by the 1920s,
if not earlier.  Whether Aeolian chose not to protect it, or tried and
failed, I don't know.

Julian Dyer