BbmMaj7b5 names three separate instructions: a minor 3rd, , and major 7th. The result is Bb, Db, Fb and A.
The flat 5th is the only change from . It must sound, or the voicing is only . This is neither a half-diminished nor diminished-seventh chord.
Also written BbmM7b5 or Bbm(maj7)b5.

Drop the third voice from the top an octave instead. The wider gap skips a string, so the muted string is part of the shape.
That result, 3–R–5–7, is the shape usually meant by drop 3. Named by its bass note, as the inversions are here, it is the 1st inversion.
More familiar jazz shapes are drop 3 than drop 2.
Contains BbmMaj7b5 and adds ninth, eleventh, sharp fifth and thirteenth.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.