What resorts are you considering? I checked availability for each of those two dates and there are a lot of available resorts with the AP for the Apr 14-18 dates. But there are only a few resorts available for Ap 15-19. There aren't any value or moderate resorts (except a very expensive CS room) available for Apr 15-19, but they are available for Apr 14-18.
I can look for a specific resort if you give me more information.