These are the differences I think I know about so far: - You can't lie to Datomic, it's immutable and has some really interesting performance characteristics because of that i.e. TTL = infinity, the downside from a legal pov is no information is really gone only redacted from now, I think the law should be updated so that redacted is enough (if not already, I'm not a lawyer) Crux can delete things not sure about performance ramifications - Datomic stores information as datoms which are single pieces of information which are easy to re-arrange at run time to be any shape of tree you like, Crux is a document store which is a small tree already, not sure what abilities there are to re-arrange the tree at query time

- storing business time in Datomic is inefficient because it has to be added to the transaction which I don't think is added to indexes, this is the primary use case of crux though

- cardinality is defined up front in Datomic which I suspect catches data integrity errors, I haven't seen anything in crux to support this

- crux doesn't support either the pull or entity syntax ( I don't know which one or why that's important, I'm a bit out of my depth now)