There´s a simple comparison that helped me a lot taking my first steps with cassandra:
Our team decided to use Cassandra as storage solution to a dataset.
I am very new to the NoSQL world and Cassandra so I am hoping to get
some help from the community: The dataset is pretty simple, we have
for each key a number of columns with values. Each day we compute a
new version of this dataset, the new version will mostly update
existing keys but could also add and delete some keys. (And we'll
build a service that queries Cassandra). A key requirement for us is
we want to keep versions of the dataset and keep N versions around,
this is in case we discover problems in the current version and need
to "roll up" to an older one. I thought about creating a Column Family
per version, this means we will create a new column family every day
and occasionally delete column families according to some truncation
policy. I know Cassandra 0.7 now makes changing schema easier, but is
this a good way to go? I would really like to hear what you guys think
is the better way to handle this. Thank you.