Difference between lon and lng
I run over these three abbreviations:
Are they equal?
Same, equivalent terms. lat/long is probably the most common, but of course "long" is a reserved word / data type in many programming languages, so you'll find other ways to shorten longitude.
In some contexts, GIS people will use long/lat (i.e. reverse order), since this is the normal X/Y coordinate reference system for a Cartesian plane.