older vs sr.

older and sr. both are adjectives.

Word	Noun	Adjective	Verb	Adverb
older	No	Yes	No	No
sr.	No	Yes	No	No

As adjectives, older and sr. are synonyms defined as:

older and sr.: used of the older of two persons of the same name especially used to distinguish a father from his son

Other synonyms of older include elder.

older (adjective)	sr. (adjective)
skilled through long experience	used of the older of two persons of the same name especially used to distinguish a father from his son
advanced in years; (`aged' is pronounced as two syllables)
used of the older of two persons of the same name especially used to distinguish a father from his son