Generally speaking, the smaller the bottle, the shorter the wine conservation time. Basically,the same wine will reach its peak faster in a normal sized bottle than in a magnum. This ismainly due to the oxidation happenning in every bottle. As weird as it sounds, all wineformats above 3L have biblical names!
Below is the guide to wine bottle sizes:

Piccolo or Split (187.5 ml): mainly used for Champagne
Half (375 ml): half a bottle of the standard 75cl size
Standard (750 ml): the most famous bottle size
Magnum (1.5 L): two standard bottles
Double Magnum (3.0 L): two Magnums bottles
Jeroboam (4.5 L): six standard bottles
Imperial (6.0 L): eight standard bottles
Salmanazar (9.0 L): twelve standard bottles
Balthazar (12.0 L): sixteen standard bottles
Nebuchadnezzar (15.0 L): twenty standard bottles.
Solomon (or Melchior) (18.0 L): twenty four standard bottles. Hoping that this would have made you thirsty or keen to read the bible!