Like intervals, all chords can be performed harmonically, (when all their notes sound together), or melodically, (when all their notes sound consecutively). In such cases, the chord is called a broken chord, or sometimes, arpeggio. In example below, the harmonic chords are shown in the top line, or chords with all of their notes sounding together. Directly below them are the broken chords (arpeggios), where all of their notes are sounded consecutively. As you can see, the notes of harmonic chords are written one above the other and the notes of broken chords are written one after the other.
Play example of harmonic chords vs. broken chords