migration vs upgradation

Hi all,
Could anyone please clarify me the below questions,

1. I am doing an database upgrade from Oracle 9i to 10gR2 and this is on Solaris 9.5 64 SPARC. My question here is, can i upgrade a database between different versions of OS? Suppose, i have a Oracle 9i database on Solaris 8 and I want to upgrade to Oracle 10gR2 on new server, which has Solaris 9.5 installed on it. Does this come under an upgrade or database migration.

Database Migration - is a process of migrating databases between different OS. Does transferring a database from Solaris 8 to Solaris 9.5 come under the database migration process?

Can any one tell the excat difference between migration and upgradation

Thanks
tmg

I would say you are doing a migration and an upgrade.
I am doing something similar.
Moving an Oracle 8 database from Solaris 5.8 to Solaris 5.10 (Migration)
then upgrading the Oracle 8 database on the 5.10 server to oracle 10 (upgrade)

you should be ok going from solaris releases as long as they are both the same version of oracle