Biggest differences between bukkit and nukkit?


I've been reading a load of bukkit tutorials to get myself familiar with how the api works. Usually I will cross reference the methods I see with the nukkit api to see if it functions the same way and is called the same thing.

My question is, at what point is the information about bukkit not going to apply to my nukkit plugins? Is there a really big difference I have not run into yet? Or, is the difference between the two just syntax?

<3 Thanks! I love nukkit! <3