Yo base your conclusions on wrondg data. There're 2 versions of SQL Expresss 2005

SQLEXPR.EXE 55.4 MB  - For 32 and 64 bit OS
SQLEXPR32.EXE 36.5 MB - 32 bit OS only

>I want to know why SQL Express Edition SP2 size is 36.4MB while the size of SP1 is 53.8MB.
>What SP1 had which SP2 does not have. I mean does it missing any features?