what is the difference between OBIEE and BI Apps
OBIEE is a reporting/trending tool where reports can be generated using OBI Answers, Published using OBI Dashboards and Delivered using OBI IBOTS. OBIEE formerly know as siebel analytics formerly known as Nquire. Now Hyperion is mergerd/combined with OBIEE and there is place for this combination in the market (I guess).
OBIEE is same as microstrategy/cognos/business objects/sap bw/ many more in market today.
clients(in real time, no one does this) can also Ad-hoc reporting by themselves with out dashboard developers
BI Apps is a prebuilt/pre-packaged/delivered/out of box Material which is developed by Oracle Corp thinking that this OOTB dashboards(webcatalog), repository, informatica adopters will be good enough for clients who expect to invest low on human resources and use the analysis tool immediately.
most of the cases, clients may end up customizing their ERP/CRM/Applications where those customizations have to be done in Informatica, DAC and BI Apps RPD.
BI Apps mean or iincludes Informatica, DAC and RPD, WEB CATALOG etc.