Macros are subroutines or fuctions written on VBScript that can be used to control QV and its objects or even to go beyond QlikView and control other software (Excel, Word or even the Operational System).
Triggers are just the events that can be associated with macros or actions. Triggers can be onOpen (when you open the document), onSelect (when you make a selection on a field), etc.
Maybe your question is more like: what is the difference between macros and actions. For this, there are some threads that discussed this before:
