From DBA perspective, below are the changes in R12.2.x version of Oracle Applications, compared to R12.1.3.
1. Dual FS: Oracle Application Release 12.2 has dual filesystems(RUN FS and PATCH FS) to facilitate Online Patching.This Requires double the mountpoint space at MiddleTier Level.
2. Weblogic Server: Oracle HTTP Server in R12.1 is replaced by Oracle Weblogic Server.
10.1.3 Home is replaced by FMW_HOME.Weblogic Server Manages all oacore, forms and oafm servers in R12.2.
3. Online Patching : Dual Filesystem and EBR feature in 11gR2 Database facilitate online patching. Online Patching minimizes the downtime required for patching.adpatch utility in R12.1.x is replaced by adop utility. adop cycle runs in 5 Phases : prepare,apply,finalize,cutover and cleanup. adop internally calls adpatch utility to run the driver files associated with adop phases.
4. APPS Password Change: After Changing Apps Password in R12.2, we need to update the new password in EBS Datasource used by Weblogic Domain.To know more about apps password change in Oracle applications R12.2, check the below link.
5. Cloning : While Cloning of R12.2.x adcfgclone instance needs to be run twice, on RUN fs and PATCH fs.From 12.2.5 Version (OR R12.AD-TXK Delta 7), we have the dualfs option which creates both run fs and patch fs during clone process.