Is FA 18:2 undifferentiated the same as linoleic acid?
It's part of an old nomenclature used in the fatty acid industry.  FA 18:2 translates to F atty A cid with 18 carbon atoms and 2 double bonds.  You can read more about these "Lipid numbers" here.  So to answer your question, there are number of fatty acids with 18 carbons and 2 double bonds, linoleic acid is just one of them.  FA 18:2 includes linoleic acid, but is not limited to just linoleic acid.