I found Redhat have many version but I am not understand what is its difference ,

1. AS vs ES , what is its difference ? as I know , the difference of these two version is only AS have technical support while ES don't have , if so , what is the difference of the disc ? which one should I use ?

2. for ia64 , for IBM power , for intel itanium , 32bit x86 , does it mean I must find the disc to install to the right server model eg , if I use itanium cpu , I must use RH for intel itanium , if I use IBM power server , I must use RH for IBM power etc ? I tried to to use the verion 32bit x86 to install different servers , it works and without problem , does it mean 32bit x86 is work for any type of server ?

3. Beta , Extras Beta , I found these type of version , is it only used to testing ? if I used for production server , I can skip to it ? thx

1 - AS and ES is the amount of memory and CPU (its mainly a License thing) - This applies to RHEL4. Version is is RHEL5 and RHEL5 Advanced Server (CPU Based)
2 - Yes you need the right type of Redhat based upon the systems Architecture. 32Bit will work as long as you get the Architecture right. 32bit will work on a 64 bit machine but not the other way round.
3 - Beta - As it says. Extras - Additional packages supplied but not always supported by Redhat.