The Hot Fill Hold method (HFH) is different from boiling water bath (BWB) which is different than pressure canning.
BWB is using traditional canning jars with metal lids and rings. The jars are filled with hot or cold product. The jars are immersed in boiling water for the prescribed time and then removed from the boiling water and allowed to cool.
HFH is used for glass bottles with PLASTIC caps. The plastic caps cannot be immersed in water. In the HFH process, a sauce with the proper pH is heated to the proper temp (usually 200F). The heated sauce is put into the glass bottle which is immediately capped and inverted. The bottles are kept inverted for about 5 minutes which allows the heated sauce to come in contact with the inside of the cap.
Pressure canning is a whole other process that is not commonly used by sauce makers.
This is explained in pretty good detail in the Hot Sauce 101 thread.
Hope this helps~