Newbie - what can you tell me about Universal's early entry?

[4orm]

I am familiar with Disney's extra magic hour but Universal is new to me. Is it only for onsite guests? Partner hotel guests? Guests that book packages? I was looking at the WWoHP... at a hotel I could use points to stay at... would EE only apply if I got the package or if I was staying at that hotel regardless? Thanks for any replies... and any other tips would be beneficial too