We relate several models of concurrency introduced in the literature in order to extend classical Mazurkiewicz traces. These are mainly Droste's concurrent automata and Arnold's CCI sets of P-traces, studied in the framework of local trace languages. Also, a connection between these models and classical traces is presented in details through a natural notion of projection. These relationships enable us to use efficiently Arnold's result in two other frameworks. First, we give a finite distributed implementation for regular CCI sets of P-traces (or, equivalently, finite stably concurrent automata) by means of bounded labelled Petri nets. Second, we present a new, simple and constructive method to relate Stark's trace automata with Bednarczyk's asynchronous transition systems. This improves a recent result in Scott domain theory.