AJAX enabled WCF Service Vs Standard WCF Service

[Simon]

Hi Guys,

In Visual Studio 2008 there is an new item template called something
like "AJAX enabled" WCF Service along with just the standard WCF Service
template.

Can anyone explain to me what the actual difference is between the two?
I can see that the AJAX enabled service has a slightly different config
file, but I'm unsure what actual difference this makes?

In particular, is the format of the data returned different when its
AJAX enabled - if so, how is it different?

Many thanks in advance

Simon