what is difference between sms 2003 inpalce up gradation and site by site migration? again how to perform both  inpalce up gradation and site by site migration migration i am looking setps 

Just do it in-place and then migrate from 07 to 12 side by side.

Thanks can i know steps please how do in-pace and then migrate from sms 2003 to sccm 2007

Its not called migration, for 2003 to 2007 its up-gradation so you can simply run the  setup and follow the documentation.

For procedures and considerations follow the below technet article

https://technet.microsoft.com/en-us/library/bb632845.aspx

sms 2003 to sccm 2007 it is up gradation inplace and site by side what is difference two methods? why it is not possible to migrate or upgrade sccm 2012?

sms 2003 to sccm 2007 it is up gradation inplace and site by side what is difference two methods? why it is not possible to migrate or upgrade sccm 2012?

Good evening SCCM Ghost, you have already asked this question before, please review the answer provided.