There are three differences

1. Symphony contains orchestral music, percussion music and some national musical instruments, but orchestral music only contains string groups: violin, viola, cello and cello.

2. Symphony actually refers to the form of composition, such as Beethoven's first to ninth symphonies. These pieces of music are very demanding in all aspects. An orchestra that can play a symphony is a symphony orchestra, that is to say, a symphony orchestra is one step higher than an ordinary orchestra, and otherwise, it is essentially the same.

3. Orchestral music is mainly composed of wind music (woodwind music, brass music) and strings (violin, cello, viola, double bass), plus common percussion music (timpani, triangle iron, etc.). Symphony includes all the instruments in orchestral music, and then more instruments are usually added, such as harp, Malimba (xylophone) and double bass.

Extended information:

About orchestral music

Orchestral music was gradually formed with the development of vocal music and instrumental music in the 16th and 17th centuries. After the 18th century, Haydn established the orchestral organization and the main melody music style; Mozart further affirmed that Beethoven wrote orchestral overtures in a symphonic and dramatic way. From the 19th century to the 2th century, the development of orchestral music reached its peak, and a large number of outstanding composers and works appeared one after another.

About Symphony

Symphony (not the same as symphony, which can be used in general) is a large orchestral music with multiple movements, which is usually composed for an orchestra. Symphony is a large orchestra suite, which evolved from the overture of Italian opera. The name of "symphony" comes from Greek, which means "to ring together". In the second half of the 18th century, it developed into an independent orchestral work, usually consisting of four movements (sometimes preceded by adagio), and some of them had more or less than four movements.

The genre of each movement is very similar to that of sonata, but the scale is larger, the music theme is greatly developed, and the orchestral method is also richer, which is suitable for expressing dramatic content. Symphony orchestra is a large-scale orchestra in modern times, which is divided into two pipes, three pipes and four pipes according to its size, that is, small, medium and large. The number of people ranges from tens to hundreds. It is usually composed of stringed instruments, woodwind instruments, brass instruments and percussion instruments. Sometimes, according to the creative intention and specific requirements of the composer and conductor, the musical instruments are increased or decreased.

References: Orchestra _ Baidu Encyclopedia Symphony _ Baidu Encyclopedia