KeePass is a light-weight and easy-to-use password manager that removes the need for you to remember many different passwords and makes it more feasible to use different passwords for each account. It manages your passwords in a secure database encrypted with AES and Twofish, which is locked with one master key or a key file.
KeePassX is a password manager or or safe that helps you to manage your passwords in a secure way. You can put all your passwords in one database, which is locked with one master key or a key-disk. You only have to remember one single master password or insert the key-disk to unlock the whole database. The databases are encrypted using AES or Twofish.