Dear friend

Greetings

Both are one and the same. 

I have used fuzzy rough sets in my papers. you may look at them.

I hope this helps.

Best regards

Dr.indrajit Mandal

Rough Fuzziness: to be used when you plan to approximate a fuzzy input under crisp knowledge.

Fuzzy Roughness: to be used when you plan to approximate a fuzzy input under fuzzy knowledge.

Dear Nouran Radwan,

As professor Ganapathy Ganesan has mentioned , Here is a conceptual difference between fuzzy rough set model and rough fuzzy set, we all know rough set deals with indiscernible elements and fuzzy set with fuzzy sets and memberships,

it is better to use rough fuzzy set modelling, when we have specified knowledge concepts but approximated concepts are not so clear (ill definition), and when problem knowledge is fuzzy concepts and approximated concepts are specified we could use fuzzy rough modelling.

You could find more details in below links;

Sincerely,

https://books.google.com/books?id=TEN5EwDkLrsC&pg=PR11&lpg=PR11&dq=Hybrid+Rough+Sets+and+Applications+in+Uncertain+Decision-Making&source=bl&ots=HVxki4ehF1&sig=BN935QCSwDfwTZ4VJLohwxhpxVE&hl=en&sa=X&ei=EIayVIq5BMPKaLXggKAM&ved=0CCwQ6AEwAg#v=onepage&q=Hybrid%20Rough%20Sets%20and%20Applications%20in%20Uncertain%20Decision-Making&f=false

or

http://www.crcnetbase.com/isbn/9781420087499

Rough-Fuzzy Set: Approximation of a fuzzy set in a crisp approximation space.

Fuzzy-Rough Set: Approximation of a crisp set in a fuzzy approximation space.  

The Fuzzy set means that the elements in a set are not determinative or changing by the observer. The Rough set means that the boundary of set congtaining some elments are not determinative or changing by the observer. The Classical set are that both the elements in the set and the boundary of the set determinative.

A rough fuzzy set is a pair of fuzzy sets resulting from the approximation of a fuzzy set in a crisp approximation space, and a fuzzy rough set is a pair of fuzzy sets resulting from the approximation of a crisp set in a fuzzy approximation space.

Fuzzy set works on features of the data whereas rough set works on attribute set of the data (crisp). Therefore, the result of rough-fuzzy hybridization set is the approximation of fuzzy input into crisp approximation space. On the other hand, fuzzy-rough set refers the approximation of crisp set into fuzzy approximation space.