===.
Diminish Chord Pattern 1
Note that the 2 chord patterns are the same but the Function is different.
C#dim7
C#, G, Bb, E = the Full Chord
C#, G, Bb, E = the Notes Played
A7b9
A, C#, G, Bb, E = the Full Chord
C#, G, Bb, E = the Notes Played
For this A7b9, the 'A' note is not played here for various reasons like; it could be played by another instrument or it is the least important note among the other 4 here.===.