No problem ALW.
In GMAW (Gas Metal Arc Welding) there are 3 basic transfer modes.
Short Circuit
Globular
Spray
These modes describe the way in which the electrode is deposited onto the parent metal. Essentially,high(er) voltage (and corresponding wire speed) deliver different transfer modes.
Most, if not all MIG welding that is done is short circuit transfer as Globular tends to cause lots of spatter and is hard to control in out position welding and Spray Transfer is for thick materials since it requires voltages above 27 volts and shielding gas with less than 15% CO2 content.
Here is a video that shows the difference in transfer modes. Take special note to the sound difference as the voltage and wire speed are adjusted to change the transfer mode.
Short Circuit will sound like frying bacon, Globular transfer deepens in tone and is more sporadic, and finally true Spray transfer will only make a slight hissing sound.
Hope that helps.