Try
system_profiler SPExtensionsDataType
(though that doesn't provide any obvious means of distinguishing between Apple and non-Apple extensions).
Thanks for that; I made a coupl'a stabs at a correct command earlier but didn't come close.
Your command returns more info than System Profiler offers, but in the same alpha format (although in a far less readable presentation), and it identifies extensions with exactly the same nomenclature; non-Apple extensions are included in the alpha order presentation and are, hopefully, readily recognizable in by their names.
Under the circumstances, I'll refer ryck to System Profiler as being the more user-friendly of the two methods of calling up the info.
