Disease

There exist many features which make you immune to disease, to avoid trivializing this aspect, these fetures only make you immune to regular disease, but they give you advantage against magical diseases.

Types of diseases:

Common Disease: Something which you encouter very often, most fall into this category, from acommon cold to the black plauge. If you have immunity agains diseases, your chances of "chatching" it are very low, meaning you will most likely not act as a carrier, spreading it to others. You will also suffer very little to zero ill effects from it.
Magical Disease: These types of diseases are rare, unnatural and often enegierered. They might not be more deadly than common disease, but their magical element makes them very unpredictable. If you have imminity against diseases, you can make every save agains this type of disease with advantage, reducing the chances of chaching it, or suffering ill effects, but not quite negating them.
Otherworldly Disease: This type of disease is very, very rare and only very powerful beings, such as gods or demigods are capabale of brining them into existance. They have the potential to wipe out whole planets and anyone, save for the most powerful beings, can be affected by them, regardless of their imunities to other diseases.