summation vs sum total

summation and sum total both are nouns.

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

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

Other synonyms of summation include sum.

summation (noun)	sum total (noun)
the arithmetic operation of summing; calculating the sum of two or more numbers	the final aggregate
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