Differences ....

Here are few varied differences one would like to know abt :

Iterator Vs ListIterator
Iterator iterates only in forward direction
List iterator can navigate bidirectional

ServletRequest Vs ServletContext RequestDispatcher
ServletRequest RequestDispatcher can take relative path
ServletContext RequestDispatcher cannot take relative path

Clob Vs Blob
Clob stores huge character type data like xml,txt, etc files
Blob stores huge binary type data like jpeg files, etc

Threads :
yeild() - returns to ready state
sleep() - returns to wait state
notify() - invoke wait state thread to ready state
notifyAll() - invoke all wait state thread to ready state

Sleep Vs Wait
sleep holds the thread till the time specified and cant be revoked within that time whereas wait holds the thread till specified time but can be revoked in the within time.

DB Cursor Vs RefCursor
Cursor :
No return type
Static
Can assign to single query
RefCursor :
Has return type
Dynamic
Can assign to multiple queries

Differences between Collections :
List :
Ordered
Contain duplicates
Vector :
Growable array
Synchronized
Multi thread
Default size to 10
Set :
Unordered
No duplicates
Hashtable :
Key-value
Synchronized
No NULLS
Ordered
Use enumerator
Arraylist :
Heterogeneous
Unsynchronized
Allow NULLS
Uses array structure to store
No default size
Map :
Interface
Associate key with Value
Hashmap :
No order
Unsynchronized
Allow NULLS
Use Iterator
Default size is 8
LinkedList :
Faster to insert/delete in between.