Difference between SmartGWT4.0d and 4.0p

Hi,

We have purchased smartGWT4.0 recently and have doubt in builds versions.
We want to know the difference between SmartGWT4.0d and 4.0p.
we are using 4.0 pro edition in our project ,we observed that in 4.1d also have pro build, can we use 4.1d instead of 4.0p.

Is it stable ?

Please let us know your comments.

Thanks.