sr. vs older

sr. and older both are adjectives.

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

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

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

Other synonyms of sr. include elder.

sr. (adjective)	older (adjective)
used of the older of two persons of the same name especially used to distinguish a father from his son	skilled through long experience
	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