Yes, there are different flavors of Oracle. However, Oracle 8 and Oracle 8i are just different versions of the same product. (Oracle 8 is 8.0.x and Oracle 8i is 8.1.x).
There is a whitepaper somewhere on the Oracle websites (metalink/technet/oracle.com that I can't remember) that explains the difference between Oracle 8i Standard and Oracle 8i Enterprise that is called "Oracle 8i: A Family of Database Products". Also, you can look at [url]http://www.oracle.com/ip/deploy/database/availability/[/url] for some general guidelines about the product lines.