Oxidation goes a little deeper. Oxidation is the off flavors caused by unwanted oxygen introduced at ANY point of the brewing process. Its been pretty much proven that on a homebrew level, oxidation on the hot side is a non issue. That being said, I'd refrain from splashing around the mash and introducing oxygen into the hot wort as much as possible. Oxygenation simply refers to introducing oxygen for yeast to use. Since the yeast utilize it, there should be none left over to cause oxidation off flavors.
Novice homebrewer here. I'm brewing a wheat beer and when I transferred the wort to the fermenter I put two gallons in first and splashed it around. The wort was probably somewhere around 110-120 F. Then I poured the rest in and added cold water to bring it to the 5 gallon mark. Any thoughts on how this will effect the outcome?