Do the student and work residency permits count as the same with regards to the five year rule?

I hear there is a rule that stipulates a person can only stay on a residency permit for 5 years and then they have to leave. If having already spent 2 years in PRC on a student residency permit would deciding to work mean i would only be eligible for a 3 year working residency permit before needing to leave, or does the 5 years only apply to the same type of residency permit? Thanks.