CouchDB & MongoDB both share one property that this comparison misses (or mentions only in passing).
Both are schema free datastores. For me, this is the biggest, most useful difference between them and traditional SQL databases, because it makes things easy that are very, very hard (or inefficient) on an SQL database.
It's probably also worth noting that other NoSQL solutions don't share this advantage. For example, Cassandra requires all nodes to be restarted to apply a schema change, which can be quite a big deal.
Not in the same sense as an SQL database. You can freely add columns and rows, just not Column Families or Keyspaces. This is because a KS+CF combo is stored in it's own file, in a certain order, so that it can be efficiently traversed using natural ordering. If you don't have this need and just need a flat K/V database, you can use a single KS+CF for everything.
Both are schema free datastores. For me, this is the biggest, most useful difference between them and traditional SQL databases, because it makes things easy that are very, very hard (or inefficient) on an SQL database.
It's probably also worth noting that other NoSQL solutions don't share this advantage. For example, Cassandra requires all nodes to be restarted to apply a schema change, which can be quite a big deal.