sql server database size shown different in properties pane while monitoring when checking  database space used,my favorites are

use indexinternals
sp_spaceused



select (sum(size)*8)/1024 as size From sys.master_files where name like 'indexinternals%'



but for a curiosity I also checked the properties of database 
but when I take the properties of the database its shows the size 380MB


Its just different on this database only ,all other databases shows correct values.Any suggestion where to look at and why its showing like that ?
Properties dialog shows data and log file size. It's the same as sp_spaceused without any arguments. Use sp_spaceused table returns size of the table (i.e., part of data file) - it never takes into account transaction log - that's the missing part in the discrepancy you see.