When blocks break, they should produce appropriate breaking sounds and particles. This is not the case for decaying leaves.
Armor stands destroyed by explosions/lava/fire don't produce particles
Anvils broken by falling or overusage do not produce particles
Gravity-affected blocks broken when falling into an invalid space do not make a sound or produce particles
Ice, snow and frosted ice do not produce particles upon melting
Blocks directly replaced by other blocks do not produce particles, make breaking sounds or drop items where appropiate