Premiere's label is incorrect and misleading.
In Photoshop you're setting the standard deviation (radius) of the gaussian kernel.
Thanks for your comments. Then, how can we deal with the Premiere's label? We already used many clips edited with Premiere, but we still looking for the meaning of value of gaussian in Premiere. Do you have any idea about that? For example, if we set 50 blurriness, then how can we deal with this number in general?
I'm not sure. But you could probably match it up pretty quickly.
Blur an image in Premiere with blurriness 50.
Open the original image and the blurred image in Photoshop, put them together in the same document and set the layer blend mode to "difference".
Then blur the original with Gaussian Blur and change the radius until it matches Premiere's result (image goes black because the 2 layers are the same).
My guess is that the numbers have the same meaning, but someone put a really wrong label on it in Premiere.