Johan Den Hann published some time ago, its Cloud Landscape Categorization Framework, which is really helpful in order to get a better understanding of the Cloud Landscape.
It consists of 7 layers and 3 main columns.
As Johan states there is a continuum from hardware to SaaS. He created these 7 layers to help categorize vendors and services in meaningful way.
The 3 main columns: compute, communicate and store are well-known distinction used on the infrastructure layer. As Johan states
“The nice thing is that it also works well on the software layers. If we look at software, and especially the object-oriented paradigm, we can make a distinction between the 3 main aspects of software: state, behavior, and messages (or data, methods, and messages, if you will). This beautifully aligns with the previous distinction between storage (vs. state), compute (vs. behavior), and networking (vs. messages).
Even for us humans we can distinguish these 3 aspects of operating with data: we store data (e.g. memorizing it, writing it down), we process data (e.g. combine, compute), and we communicate data (e.g. speak, write).”
Each cell is well documented on the site and there is a cool feature to overlay the framework with various cloud offerings. It allows you to quickly get an impression which vendor is offering, what kind of solution.
For example Amazon Web Services