Recessed Tips are generally used for higher heat applications where longer electrical stick-out is required or in cases where the nozzle may touch the work piece (tack, spot, and stitch).

Flush Tips are generally used where a shorter electrical stick-out is used sometimes resulting in shorter/tighter arc lengths. This brings the tip closer to the work piece.

Protruding Tips are generally used when welding open root pipe or any joint that requires the welder to get into a tight weld joint. However, the down side to this is the chance of arcing the tip to the work piece, which could damage front end parts resulting in downtime needed to replace.