sum total vs summation

sum total and summation both are nouns.

Word	Noun	Adjective	Verb	Adverb
sum total	Yes	No	No	No
summation	Yes	No	No	No

As nouns, sum total and summation are synonyms defined as:

Other synonyms of sum total include sum.

sum total (noun)	summation (noun)
the final aggregate	the arithmetic operation of summing; calculating the sum of two or more numbers
	a concluding summary (as in presenting a case before a law court)
	the final aggregate
	(physiology) the process whereby multiple stimuli can produce a response (in a muscle or nerve or other part) that one stimulus alone does not produce