MSN 590 to 650 are old aircraft and probably have the old RAT which is affected by the lowering of the gear as it sits in airflow disturbed by the noseleg. For this reason, the aircraft goes onto batteries only which last 22 minutes. If you go around and can get the gear up, there is a procedure for re-instating the emergency generator, powered by the Blue system through the RAT. Later aircraft (for which it seems the more recent manual in your possession has been written) have an improved RAT fitted which will continue to work once the gear is lowered.
Although the later document says "All" it will refer to all the aircraft in the fleet of the operator for which that manual has been written. For example, if it was an easyJet manual, it will say ''All'', as all their airframes were dleived after the new RATs were fitted as standard. This highlights the dangers of using manuals not written for your aircraft. It's important with any aircraft to check the manual is applicable for the airframe your are flying. Even among fleets in the same airline there can be large differences.