Difference between BJJ and Judo ground work/ground sparring?

I have been doing BJJ for two years and I recently moved. A gym right down the street from my new house has a Judo club who does ground work on some nights. Going from BJJ to Judo what should I expect in terms of ground work and attitudes. I don't mean the rules but how techniques are used (I did not see much closed guard) and any other things you noticed if you have experienced both.