This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
The Reader/Writer class hierarchy is character-oriented, and the Input Stream/Output Stream class hierarchy is byte-oriented.
Basically there are two types of streams.Byte streams that are used to handle stream of bytes and character streams for handling streams of characters.In byte streams input/output streams are the abstract classes at the top of hierarchy,while writer/reader are abstract classes at the top of character streams hierarchy.
Hope this answers your question somehow.