[Callers] Square through vs Cross-trail

Square-through vs Cross-trail Can anyone tell me what the difference is between these two figures, if any? They show up in various different dances in my collection but they both seem to be the figure that in English country dance we'd call "2 changes of rights and lefts" which is to say right hands to the person across from you (either neighbor or partner, depending on where the dance has taken you so far) and then left hands to the person in your minor set who's next to you in line (again, either N or P). And in ECD those 2 changes can sometimes start along the line instead of across, which I assume can happen in contras as well though I haven't yet encountered it. And can anyone point to a really thorough online glossary of contra terminology? Kalia