The syntax is different in this poem because the words are in an unusual order.
Syntax is the arrangement of words and meaning.
As you can immediately tell, e.e. cummings likes to break the rules. He does not capitalize. He uses punctuation sparingly. He wants you to stop and think about what he is really saying. He does not want anything to separate you from the work.
In the first line, the speaker comments that feelings, not words, should come first. Then he proceeds to write the feelings before the words.
will never wholly kiss you;
wholly to be a fool
while Spring is in the world
Putting the words in a sensible order would not have the same effect. It does not put the important part first, which is the need to kiss, and the feelings of never being able to really express one's feelings completely.
Love is not about words, so you can never fully express your feelings in words. This is the message of the poem, and the reason cummings does not use traditional syntax.