The standard type of deep groove ball bearing with stop groove, the code is N, the bearing with stop groove and snap ring ,the coded is NR, in addition there are ZN, ZNR and other structural variants.
the function of the deep groove ball bearing can bear the radial load, the N type groove and the bearing with the retaining ring can limit the axial displacement of the bearing, this bearing simplify the axial structure of the bearing housing and reduce the axial dimension.
bearing with with Snap Ring are often used in working parts such as automobiles and tractors where the axial load is not large.
There are some bearing number for your reference :6004ZZNR 6005ZZNR 6006ZZNR 6007ZZNR