The difference between quarter notes and eighth notes, the relevant content is as follows:

1. Quarter Note (Quarter Note)

The quarter note is the most basic One of the rhythmic units, in 4/4 time (one of the common time signatures), the quarter note occupies one beat of time. Its duration is a quarter note, usually represented by a solid oval symbol. Quarter notes have a relatively long duration and therefore appear relatively infrequently in musical scores.

Second, eighth note (Eighth Note)

Eighth note is a shorter duration than quarter note. In the same 4/4 beat, eighth note are half the duration of a quarter note, so they have two eighth notes in one beat. Eighth notes usually have a solid oval symbol, but have an additional tail (i.e. stem) on the note head. Eighth notes have a shorter duration than quarter notes, so they appear more frequently in the score.

3. Difference:

Duration: The most intuitive difference is that their duration is different. A quarter note lasts longer and takes up one beat, while an eighth note lasts shorter and requires two eighth notes to fill a beat.

Frequency: In a musical score of the same length, eighth notes usually appear more frequently because they last shorter and are more suitable for expressing complex rhythms.

Symbol shape: Although they are both solid oval symbols in shape, eighth notes have an extra stem on the notehead, which is easier on the eyes compared to quarter notes identify.

4. Application in music:

Quarter notes and eighth notes often appear alternately in music to express different rhythms and musical expressions. In rhythmically complex or fast-paced passages, eighth notes may be more appropriate to convey a faster rhythmic feel, while in more steady or slow tempos, quarter notes are more common.

For musicians, it is crucial to understand and master the timing and rhythm of different notes, because they directly affect the performance, rhythm and expression of music. Through the rational use of quarter notes and eighth notes, the music will be more vivid and rich, and can better express the composer's intention.