Milk pox and Smallpox

Milk pox noun - A mild form of smallpox caused by a less virulent form of the virus.

Smallpox and milk pox are semantically related. In some cases you can use "Smallpox" instead a noun phrase "Milk pox".

Smallpox noun - A highly contagious viral disease characterized by fever and weakness and skin eruption with pustules that form scabs that slough off leaving scars.

Milk pox and smallpox are semantically related. Sometimes you can replace phrase "Milk pox" with "Smallpox", this terms are similar.