What is the difference between austenite stabilisers and ferrite stabilisers ?

Austenite stabilisers have the effect of extending the temperature range over which austenite is formed. Such elements are carbon, manganese, nickel, copper and cobalt.
Ferrite stabilisers have the effect of extending the temperature range over which alpha and delta ferrite are formed, which consequently reduces temperature range over which austenite is formed. Such elements are silicon, chromium, molybdenum, tungsten, titanium and niobium.