Faith,
April is a great time to travel to the Walt Disney World Resort. I have a special fondness for Disney in April since that is when I celebrated our honeymoon there almost 11 years ago. It will be here before you know it. I hope you are planning to experience the
International Flower and Garden Festival that will be going on during your visit.
To answer your question, according to the official website in regards to
Extra Magic Hours, it states they are "a special benefit for guests of Walt Disney World Resort Hotels, Walt Disney World Swan and Dolphin Hotels, Shades of Green Resort, and Hilton Orlando Resort (on Hotel Plaza Blvd.)." So, as long as you stay in one of those, you will reap the benefits of this wonderful service. Many guests might consider some of the neighboring hotels that are a very short distance from Downtown Disney as "on property" or a Walt Disney World Resort hotel (which they are not), so that may be where some of the confusion lies. I hope this clarifies this for you.
Have a magical spring in Walt Disney World!
~Allison L