Board Thread:Naruto Discussions/@comment-1512913-20180923130046/@comment-3279282-20180924173139

It's actually pretty simple:

The requirement for Magnet Release is two basic natures, Rasa's profile gives us these natures => Magnet Release's natures are confirmed by inference.

The requirement for medical ninjutsu is either Yin or Yang, Tsunade's profile gives us the correct nature => medical ninjutsu used by Tsunade are Yang.

The difference is that not all medical ninjutsu are automatically Yang, the same way that not all elemental kekkei genkai are made up of Wind + Earth.