Some parts of the Civil Procedure Rules seem to be parts of the rules, other seem to be labelled as Practice Directions, however they are still numbered as in the same scheme as the other parts.
Then there is the Criminal Practice Directions which makes it handy to conveniently refer to the Civil Procedure Rules as CPR without risking confusion with the criminal ones because I suppose they would be CPD if abbreviated. But what other significance does this difference in terminology have?