Is 2GB required/needed?

[Tullphan]

I was just curious how much difference there was between phones that had 2GB of ram & those that only had 1.
Is there that much performance difference?

 

[Leonel Funes]

Usually there's a noticeable difference when multitasking lots of apps. But other things like processor, resolution, etc can also affect that difference.

 

[Zachary Boddy]

There is a considerable amount of performance difference.
However, RAM will not overtly affect every day performance, and will generally only affect performance with applications that require a lot of RAM.
If you don't already know, RAM stands for random access memory, and it's where your device stores information to quickly access, such as information about an open application. The more you plan to do at a time, the more RAM is required, because there will be more information your device will have to access quickly. RAM is not really reliant on the power of the processor, which provides the necessary computing heft to actually run the applications. The amount of RAM simply dictates the speed at which you're able to switch between open applications, multitask, and the fluidity that you'll be able to access applications that take a lot of RAM to run in the first place (graphic intensive games) or possess a lot of information.
Depending on your purposes, an extra GB of RAM can be a considerable blessing. No matter what, it can never hurt to have that extra bit of RAM and if you're going to buy a phone where the amount of RAM is an option, it's usually a good idea to spend a little more to get it.
Things such as screen resolution will also affect performance, but don't really have much to do with RAM. That's more processor related.