What are the differences between the Alfine 8 and the Nexus 8?
Another significant difference is that the nexus is supplied with a grip/twist shifter:



And the Alfine has a trigger/pod shifter:



Both shifters are intended to be used with the right hand.

Also note that the IGH has variable pull amounts between gears, so you cannot substitute a linear pull shifter from a derailleur setup.

Also see Installing Alfine shifter with nexus 8 hub