Unlock and Jailbreak

[Jasonbot]

Is there a difference between unlocking and jailbreaking an iPhone?
If I unlock the iPhone do i need to Jailbreak it?
And finally, Which of the two bricks the iPhone after installing updates?

 

[JadawinUK]

As far as I can tell:

You need to jailbreak the iPhone to do anything Apple doesn't want you to.
That includes unlocking, but you don't need to unlock the iPhone after jailbreaking, you could just be installing a few 3rd party apps.
And I guess no matter if you jailbreak or jailbreak+unlock, Apple will brick your iPhone with an update.

 

[CWallace]

Is there a difference between unlocking and jailbreaking an iPhone?
If I unlock the iPhone do i need to Jailbreak it?
And finally, Which of the two bricks the iPhone after installing updates?

You must first jailbreak the iPhone before you can unlock it.

Updating the firmware of an unlocked iPhone to a new version (so unlocked 1.0.2 to 1.1.1 or unlocked 1.1.1 to 1.1.2) seems to be the most likely way to brick a phone.

Some jailbroken, but unlocked, phones have been bricked via the update, but so have some unmodified iPhones.

So it is unlikely Apple is deliberately trying to brick jailbroken phones (since the update wipes the jailbreak, anyway), but they may be intentionally bricking unlocked phones.