discriminatory vs preferential

discriminatory and preferential both are adjectives.

Word	Noun	Adjective	Verb	Adverb
discriminatory	No	Yes	No	No
preferential	No	Yes	No	No

As adjectives, discriminatory and preferential are synonyms defined as:

discriminatory (adjective)	preferential (adjective)
being biased or having a belief or attitude formed beforehand	manifesting partiality
manifesting partiality
capable of making fine distinctions
containing or implying a slight or showing prejudice