Greaseable 30-60794A4
Non-Greaseable 30-879194A02 (sealed)
Ones that can be greased will last longer IF they are greased regularly and water does not make it into the boot. These allow more space for dirt and water to make it into the bearing because they are not sealed
Ones which are sealed and not greaseable keeps dirt an water out better then the others. They are not 100% sealed so if water gets in, there is a better chance it will not effect the bearing, or it will take more time before it does.
Have been unable to find the greaseable type, and for the most part they are no longer made.