from http://groups.google.com/group/mongodb-user/browse_thread/thread/4335db5e9f343dec :
> http://www.mongodb.org/display/DOCS/Performance+Testing > > The "problem" is that MongoDB is so fast, performance tends to be > limited by driver performance :) > > The main differences between MongoDB and CouchDB are speed and query > model. > > 1) MongoDB is very, very fast. We can do inserts north of 20k/sec, > where on CouchDB on the same hardware, about 250-300/sec is the max. > > 2) The query models are quite different - MongoDB has a query model > that is direct, uses indexes, and very similar to the model you might > be used to in an RDBMS (doesn't use SQL though). CouchDB uses a > "view" system which, while very nice, doesn't allow arbitrary queries, > and limits to what you can express in a key/value lookup. > > Also, MongoDB's storage format - while akin to JSON - goes beyond JSON > by adding a few types like date, which is important for querying...
