SQLite Forum

Column ordering and space saving
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Also note that SQLite has almost no fixed-length datatypes.  It does not support fixed string sizes like 'CHAR (20)'.  The integer '1' takes less space for storage than the integer '4', which in turn takes less space for storage than the integer '4444444'.

SQLite is designed to be used inside things like GPS units and drill controllers, with tiny amounts of storage space.  It has to be far more space-efficient than PostgreSQL.  Which is not saying anything bad about PostgreSQL in comparison with other client/server systems.