Jailbreak – Normally, you can only
download iPhone applications from
iTunes
App Store.
By jailbreaking the iPhone, it brings you ample
opportunities to install 3rd party iPhone applications which cannot be
put up on App Store, via Cydia.
Unlock – Unlock refers to the
process
by which your iPhone can use SIM card from any carrier. By going
through the unlock process, your iPhone is allowed to use any carrier.
Jailbreak Tools for iPhone