Question: In a song I am learning, there is a section of the song that has the chord progression G#m | A#m7b5 | B6
I sometimes get the fingerings wrong and use dimished 7th chords on guitar instead of m7b5 chords and in this case I actually think the dimished7th chord sounds good too. So I wanted to ask, what is the difference functionally between the two? They both seem to work in most situations as leading tone chords to a tonic chord one semitone above (B in this case).

Answer: 
I don't have much to add to other posts concerning the analysis, however I'd like to point another point. In some cases indeed either diminished and half-diminished chords might provide good harmonization of a melody, however they sound substantially different. If you play one or another randomly, due to mistakes, it might be very confusing for the rest of the band. It is very different from substituting e.g. Cmaj7 with C6, which can be innocent 90% of times.
Do m7ba and Do dim7 are exactly the same chord:

```
Do m7b5 = Do dim7
 Do (root)
 Mib (minor third)
 Solb (flat fifth)
 Sib (seventh)

La# m7b5 =  La# dim7
 La# (root)
 Do (minor third)
 Mi (flat fifth) (perfect fifth would be Mi#)
 Sol# (seventh) (mjor seventh would be Sol##)

```

Anyway, it sounds weird to call A# dim7 and Gm#, are you sure it wouldn't be Abm and Bb dim7 instead?

What geometry for both chords are you using on guitar?