Variola and Variola major

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

Variola major is a synonym for variola. In some cases you can use "Variola major" instead a noun "Variola".

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

Variola is a synonym for variola major. You can use "Variola" instead a noun phrase "Variola major".