One of the major issues with the actor-network methodology is that there is no ready to used steps/procedures on how to go about operationalizing the various actor-network related concepts. Many of the concepts are dispersed amongst the writings by Latour, Callon, Law, Bijker, Akrich, Hassard, and few other authors. One of the most informative sources is the book "Actor Network Theory and After" by Law & Hassard.
As actor-network theory and methodology got translated into ANT, interestingly enough we see here a theory and methodology a subject of its own theorization through the concept of translation and inscription, many researchers have tried their own particular attempts to operationalization of the concepts relevant for their line of inquiry.
The point I'm trying to make is that we have bits and pieces of attempts to operationalize various actor-network related concepts; however, we lack an overall framework. The answer to why is this is pretty much provided in the above-mentioned book in the chapter "On recalling ANT" (by Latour) stating that actor-network was only meant to be a way of doing ethnomethodology and not a theory (p. 19). So, when people talk of ANT it usually means the theorizing of actor-network in various forms and flavors, while actor-network is more of a way for doing ethnomethodology.
Latour makes the argument that the actual acronym ANT is not simply an acronym. BUT, it is a result of the process of translation by the way which actor-network theory and methodology became ANT (with various flavors). So, the process of translation produced multiple ANT-s, each ANT stressing on different concepts as related to the actor-network methodology/theory.
So, as a result it would seem that ANT has different meanings pertinent to the context and the line of inquiry it is used and applied to. The process of translation is given as the reason.
Latour explains this very clearly in the chapter "On recalling ANT".