Bandoneon vs Accordion: What's the Difference?
Both are bellows-driven free-reed instruments. The chromatic button accordion Julien Labro plays produces the same pitch whether the bellows are opening or closing. The traditional tango bandoneon is bisonoric: most buttons produce different pitches depending on bellows direction. Their note layouts and playing systems also differ, with variations existing within both instrument families.
The difference
is in the playing.
A quick comparison of the traditional tango bandoneon and Julien’s chromatic button accordion. Other systems exist in both families.
Bandoneon
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Chromatic button accordion
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The manuals
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Buttons on both sides, with different note layouts for the left and right hands.
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Chromatic buttons on both sides. Right-hand layouts vary between instruments, as do left-hand systems.
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Push & pull
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Different notes.
On the traditional tango bandoneon, most buttons change pitch with bellows direction: bisonoric. |
The same note.
A button produces the same pitch whether the bellows are opening or closing: unisonoric. |
Building harmony
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Individual notes, combined by hand. Chords and voicings are formed by the player; there are no preset chord buttons.
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Julien’s instrument uses free bass. Individual pitches can be combined into bass lines, chords, and voicings. Other accordions may use Stradella bass with preset chords, or converter systems that switch between standard and free bass.
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These are model-specific differences. Some accordions are bisonoric, and some bandoneons are unisonoric. Piano accordions have keys on the right-hand manual instead of chromatic buttons. See sources.
European roots.
Different journeys.
Both instruments produce sound by sending air through vibrating metal reeds. From that shared principle, different designs, playing systems, and musical traditions emerged.
- 1829Vienna
- Cyrill Demian and his sons Karl and Guido submitted a description and drawing of their Accordion on May 6, 1829. This was a milestone in the naming and patent history of the accordion, rather than the invention of free-reed instruments as a whole. TU Wien archive
- Mid-1800sGermany
- The bandoneon emerged from the German concertina tradition. Its development is closely associated with Heinrich Band, whose work helped shape and popularize the instrument and its name, although its history is more complex than a single-inventor story. Berlin instrument museum
- c. 1870–1880Río de la Plata
- The bandoneon reached the Río de la Plata through European migration and became increasingly established in Argentina and Uruguay. By the early 20th century, it had become a defining voice of tango. Composers including Astor Piazzolla later carried that sound beyond the dance floor and into concert music. Berlin instrument museum
Bandoneon.
Every chord, by hand.
The bandoneon belongs to the concertina family. Its buttons do not follow a piano-style sequence, and the left and right hands use different layouts. On the traditional tango instrument, changing the bellows direction also changes most notes. Piazzolla wrote Aconcagua for bandoneon and orchestra, and Julien performs it on bandoneon. Julien also performs Piazzolla’s Four Seasons of Buenos Aires in versions for bandoneon and string orchestra and for full orchestra.
Both hands play individual notes while opening and closing the bellows. Melody, bass, and harmony are built by the player, with bellows direction forming an integral part of the fingering as well as shaping the phrasing.
Its connection with tango is central, but its repertoire also reaches into chamber music and concertos.
Accordion.
More than one system.
Julien plays a chromatic button accordion, with buttons rather than piano-style keys on the right-hand manual. Different right-hand layouts exist, just as left-hand systems vary between instruments. The same button produces the same pitch whether the bellows are opening or closing.
Julien’s instrument uses a free-bass system, with individual pitches that can be combined into bass lines, chords, and voicings rather than preset chord buttons. Other accordions use Stradella bass with preset chords, or converter systems that can switch between standard and free bass.
For Julien, the accordion is a concert instrument and a musical voice across jazz, chamber music, contemporary music, and orchestral repertoire.
A third voice.
The accordina.
The accordina is a hybrid of accordion and wind instrument, combining free reeds and a chromatic button keyboard with a mouth-blown air supply. Its two side flaps allow the player to modulate the sound, drawing on a technique associated with the harmonica.
André Borel developed the accordina in France in the late 1930s and patented it in December 1943. The instrument began to be manufactured commercially in the 1950s, but production eventually ceased before the accordina was revived by later makers.
Today, the accordina has found new life in jazz, contemporary music, and other settings. Julien plays it alongside accordion and bandoneon.
From the hands
to the music.
Hear Julien with guitarist Jason Vieaux across two recordings that reveal the different voices of these instruments.
A few more distinctions.
Is a bandoneon just a small accordion?
No. The bandoneon belongs to the concertina family. It shares the free-reed principle with the accordion, but its note layouts, bellows behavior, and way of building harmony differ.
Can an accordionist switch straight to bandoneon?
The free-reed sound principle is shared, but the note maps and bellows coordination differ. Performing on one does not mean the other uses the same technique. Julien performs on both; this is not a claim about how quickly a player can learn either instrument.
Sources & further reading
Sources reviewed September 2026.
Museum records, instrument makers, archives, and Julien's program note.
- Musikinstrumenten-Museum Berlin: The Accordion Free reeds, construction, and keyboard systems
- Musikinstrumenten-Museum Berlin: ¡Che Bandoneón! German origins and arrival in Argentina
- Hohner: Accordion systems Standard bass, free bass, and converter instruments
- Omar Caccia: Bandoneon keyboard systems Unisonoric and bisonoric systems, with Fabio Furia's account
- TU Wien Archives: Demian's Accordion, 1829 Demian’s submitted description and drawing, 1829
- National Music Museum: Borel accordina Object history and sound mechanism
- UMS: The Big Squeeze, 2014 · PDF Julien Labro's program note
- Accordinas: History of the accordina Patent date, commercial production and later makers