Are 'plus' and 'summation' synonym?

[aclueless]

Please for give my ignorance (being a non-English speaker), but I find it's hard to think that 'plus' and 'summation' synomym:

https://en-word.net/id/oewn-00873785-n

addition, plus, summation the arithmetic operation of summing; calculating the sum of two or more numbers “the summation of four and three gives seven” “four plus three equals seven”

It's weird to say: four summation three equals seven instead of four plus three equals seven

Are they actually the same?

[jmccrae]

The use of 'plus' in the example is as a preposition not a noun.

I would suggest that we remove this member from the sense.

Also, looking at other dictionaries we might want to add 'plus' as a synonym of 'plus sign'