Here’s a way I came up with to think about the differences between the different “as a service” offerings.
IaaS (Infrastructure as a Service) is like renting a kitchen full of ingredients and utensils
PaaS (Platform as a Service) is like buying an undecorated cake…you can do whatever you want with it, but you start with cake, it can’t become meatloaf or pancakes or anything else you could normally make in a kitchen
SaaS (Software as a Service) is like catering…you get the cake you want with some customizations delivered to you
IaaS is the most flexible and requires the most work
PaaS is in the middle between flexibility and effort
SaaS is the most rigid and requires the least effort