What Is an Orchestra? Instruments, Sections, and How It Differs from Other Ensembles

An orchestra is a large instrumental ensemble built from four families—strings, woodwinds, brass, and percussion—led by a conductor who shapes tempo, balance, and interpretation. The term covers a range of sizes: a chamber orchestra might field 15–45 players, while a full symphony orchestra can exceed 100. If you are trying to understand what you are hearing at a concert, or deciding whether a given ensemble fits the music you want to play or attend, the sections below break down the standard lineup and where the boundaries between orchestra types fall.

The Four Instrumental Sections

Strings

The largest section, and usually the melodic and textural backbone. Standard members:

• Violin (divided into first and second violins)
• Viola
• Cello
• Double bass

A full string section may number 60 or more players; the string count is often what separates a "chamber" from a "symphonic" orchestra.

Woodwinds

Color and solo lines, often in pairs or triples:

• Flute (sometimes doubling piccolo)
• Oboe (sometimes doubling English horn)
• Clarinet (sometimes doubling bass clarinet)
• Bassoon (sometimes doubling contrabassoon)

Brass

Power and projection, typically four to five players per section in a full orchestra:

• French horn
• Trumpet
• Trombone
• Tuba

Percussion

Rhythm, accent, and effect. Core instruments include timpani, snare drum, bass drum, cymbals, and mallet instruments such as xylophone or glockenspiel. Larger scores add harp, piano, or extra percussion.

What the Conductor Does

The conductor does not play an instrument during the performance. The role is to:

• Set and maintain tempo
• Cue entrances so sections start together
• Balance volume between sections
• Shape phrasing and dynamics across the whole ensemble

In rehearsal, the conductor also decides interpretation—how fast, how loud, where the music breathes—and communicates that to the players. A new music director can therefore change how a familiar piece sounds from one season to the next. The Great Falls Symphony, for example, opens its 68th season on October 10, 2026 with the debut concert of new Music Director Robert Kahn, a program including Mozart's Overture to The Marriage of Figaro, Rachmaninoff's Piano Concerto No. 2, and Dvořák's Symphony No. 9 ("New World").

Orchestra vs. Other Ensembles

The practical distinction is scale and repertoire. A string orchestra can play Vivaldi's Four Seasons; a full symphony orchestra can also play it, but with a larger, heavier sound. A wind ensemble cannot play a Dvořák symphony as written because the string parts have no equivalent.

Orchestra and Choir Together

Many orchestras perform with a symphonic choir, alternating or combining forces. The Great Falls Symphony's November 15, 2026 program Lux Aeterna is a clear example: the Symphonic Choir opens with a cappella works under new Choirmaster Jay Gregg, the orchestra then plays Vivaldi's Four Seasons, and both groups combine for the closing Lux Aeterna. If you are choosing a concert, this format gives you both choral and orchestral sound in one evening.

What to Expect at a Live Performance

• Arrive before the downbeat. Latecomers are usually held until a suitable pause.
• Applause between movements is optional. Modern audiences often wait until the end of a multi-movement work; either is acceptable.
• Programs list the order of pieces. Use it to follow sections and soloists.
• Film-with-orchestra concerts project the movie in HD while the orchestra plays the score live—the Great Falls Symphony's January 16, 2027 Jurassic Park performance follows this format.

Choosing Which Ensemble to Hear or Join

• Want the full symphonic sound? Look for a symphony orchestra program with a major Romantic or modern work.
• Prefer clarity and intimacy? A chamber orchestra or string orchestra suits Baroque and Classical repertoire.
• Play a wind or brass instrument? A wind ensemble is the natural fit; orchestral wind sections are small and competitive.
• Want to sing? Look for a symphony with an affiliated symphonic choir, such as the Great Falls Symphony & Symphonic Choir.

Season tickets and individual concert details for the Great Falls Symphony's 2026–2027 season are available through the organization's website; check the "Plan Your Experience" page for visitor information before attending.