“there’s no halachic or hashkafic difference between giving Halloween candy to your neighbors on Oct. 31 mipnei darkei shalom than giving Christmas presents to your neighbors on Dec. 25 mipnei darkei shalom.”
I still disagree as I provided 2 differences. One based on origin. and the other based on the Remah “אִם אֶפְשָׁר לוֹ יִשְׁלַח לוֹ מִבָּעֶרֶב” which is easily doable with Christmas but not Halloween.
However if in your opinion this is not a distinction, and in fact the mailman insists on getting his gift on Christmas much like they insist on getting their candy on Halloween. In that imaginary scenario, you are right, there is no difference (aside from the other one I mentioned) and both are muttar.