You said that the difference between 3/4 and 6/8 is that the former is divided into 3 groups of 2 and the latter is divided into 2 groups of 3, but how do i identify that in songs which arent divides into those groupings of notes.
start by just finding the beat, and then check to see if they go in groups of 4...... 99% of the time they probably do. if not, then go ahead and open an investigation and put your top detectives on the case. good luck