Hi Jamie!
Disney PhotoPass Service is an awesome way to capture photos from your family's Walt Disney World vacation. It's so easy to use - just find one of the hundreds of Disney PhotoPass photographers on property and have your photo snapped. The first time you do this, just ask for a Disney PhotoPass card and then present that card each time after that for the rest of your vacation. The service is absolutely free, and once you get home you can log into the Disney PhotoPass site, add your card number(s) and see all your photos online. You can then purchase any individual photos you like as either digital downloads or prints.
Memory Maker, which recently replaced PhotoPass+, uses the Disney PhotoPass service and builds on it. By purchasing Memory Maker, you get digital downloads of ALL your photos at the end of your vacation. You can also add photos from select attractions and character dining spots to your Memory Maker, which is one of my favorite things (and a reason I think it really is a great value). It's completely digital, so you can view, download and share your photos just minutes after they're taken. Once you're home, you'll then be able to download all the digital files and have them printed in any way you prefer. There's no limit to the number of photos or the number of times you can download them. If you're interested in Memory Maker, the most affordable option is the advance purchase, which requires a 3-day waiting period before you can start adding photos. You'll then have 45 days from when the photo was taken to download it off your account.
I hope that helps explain the two services, but if you have any other questions, just let us know.
Beth