Sydney: inn units or outer houses?

Hi everyone.

I'm helping my sister find an investment property in a Sydney suburb with good capital growth and ive identified either a 2 bed apartment in the Parramatta area or a 3 bed house in the Penrith / Campbelltown area would be suitable for her price range of $250-300k. She has no preference of property type and just wants one that will gain maximum capital growth in the short - medium term.
My question is what does everyone thing about the potential capital growth of semi-inner apartment(20km from cdb) vs outer house(40km from cdb)?