Hello Susann!
This is a great question as understanding the two options can be a bit confusing. Let me see if I can help.
Disney"s PhotoPass Service is easy to use - just find one a Disney PhotoPass photographer and join your family in the picture! Then ask the photographer for a Disney PhotoPass card and you can then use it for the rest of your vacation. At the end of your vacation (or, even during your vacation) you can log onto the Disney PhotoPass site, add your card number(s) and see all your photos online. You can then choose and purchase any of the photos you like.
Memory Maker builds on and, in my opinion, improves on PhotoPass. With 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. In fact, sometimes, when I log on after a great day in the parks, I am surprised by what appears in my account! 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. Make sure you order your Memory Maker at least three days before your need to use it- that way you get a discount!
For my family, Memory Maker is definitely the way to go.
See ya real soon!
Anne