CouchRest vs ActiveRecord Callbacks

[viatropos]

In what ways do CouchRest callbacks differ from ActiveRecord
callbacks?

I see from the ActiveSupport docs that "run_callbacks" returns a
boolean:

run_callbacks(kind, options = {}, &block)

Runs all the callbacks defined for the given options.
If a block is given it will be called after each callback receiving as
arguments:
* the result from the callback
* the object which has the callback
If the result from the block evaluates to false, the callback chain is
stopped.

Does CouchRest's "run_callbacks" work as such? How does it differ?
How does it accomplish the same thing?

Thanks,
Lance