Just a slight clarification if I might add... GMAW as well as GMAW-S are both the same process but, the real difference between the two are the methods of transfer...
In other words: Short circuiting, STT (Surface Tension Transfer) or RMD (Regulated Metal Deposition), Globular which really isn't desirable, Spray, and then there's GMAW-P that could conceivably represent a whole slew of different types of metal transfer under the "umbrella" of Pulse depending on whether, or not one sets the various options available in a variety of brand name power sources which may or may not include the same options or capabilities to varying degrees of repeatability... For instance, some of the older power sources offered what is now relatively speaking a very limited overall pulse frequency capability, and for the most part when compared to current offerings, no real level of customizing the waveform to what most current power sources can achieve presently through a variety of built in design features that vary from brand name...
Then there is also the fact that the older commercially power sources couldn't even produce true square wave rectification as compared to what is essentially the current minimum standard - capability wise in order for a commercially available power source to even be considered as offering basic pulse transfer... Then there's variable polarity pulse transfer which inone of it's earliest forms was developed by NASA... Then Synergic Pulsing which simply put (and I'm using only one example here so, please bear with me Larry ;) ), is considered when the parameters which determine arc power are programmed into the unit, so they can be adjusted using a single control as opposed to the adjustment of individual parameter controls such as found on a traditional GMAW power source...
If pulse welding, the arc power parameters are: wire feed speed, background amperage, peak amperage, pulse frequency and pulse width... If non-pulse welding, then the arc power parameters are: wire feed speed, arc voltage and inductance, and these parameters may differ from one manufacturer when compared to another as well as having or not having other specific parameter controls separate from the example I used which can be found in the earlier versions of Synergic pulse controls...
Then there's what is known as "Synergic Pulse on pulse" which has been around for some time although is relatively new on a commercial basis, and a similar concept is being applied to GTAW also whereby the arc power parameters are combined into either one or more individual controls, or combined to lessen the overall amount of individual parameter controls in order to program as well as store these customized parameters in the CPU, or in a separate storage device found in the power source...This also depends on which brand manufacturer design configuration is being used, and how it interfaces with the person who can either customize the program design via laptop computer or in some cases, just chooses from pre-stored & pre-programmed parameter choices available to the operator which can also be individually fine tuned even further with adjustments that will for instance, trim the voltage slightly enough to produce a slightly different result depending on what the operator is seeking as well as other fine tuning options.
The wire feed pulse rate is also controlled with a separate set of individual controls, and some power source configurations even have separate controls for pulsating the flow rate of the shielding gases being used also... So, until all of these parameters can be considered into separate methods, or different classes of various methods of transfer, and then converted into some form of standardization with respect to one being able to somewhat calibrate power sources from different manufacturers in order to achieve a more refined capability of repeatability with regards to parameter settings resulting in identical weld deposition & quality characteristic profiles from power source to power source no matter which brand name is being used - these sometimes "mind blowing" variations from the standard methods of metal transfer found in both GMAW and more recently, in newer Synergic Pulse on pulse GTAW offerings will continue to give the various welding code committee bodies headaches for some time to come!!! ;) :) :)
Respectfully,
Henry