What is the difference between a PowerFlex 40/40P Safety Module vs the PowerFlex 525 STO Function?

This article explains the difference between the PowerFlex 40/40P Safety Module vs the PowerFlex 525 STO Function.

PowerFlex 40/40P

The DriveGuard® Safe Torque-Off option, when used with PowerFlex 40P drives
and other safety components, provides a safety function which inhibits torque
generation in the motor(s) powered by the drive. When used with PowerFlex 40P
drive, the DriveGuard Safe Torque-Off option has been certified to meet the
requirements for SIL 2 according to EN/IEC 61800-5-2 and IEC 61508, and
PL d and Category 3 according to EN ISO 13849-1. The DriveGuard Safe
Torque-Off option is just one component in a safety control system.
Components in the system must be chosen and applied appropriately to achieve
the desired level of safeguarding.
PowerFlex 525
The PowerFlex 525 drive is shipped with a jumper installed between I/O
terminals 01 and 11. Remove this jumper when using I/O terminal 01 as a stop or
enable input. An alternative is to use the Safe Torque-Off feature embedded in
the PowerFlex 525 drive. The Safe Torque-Off function disables the drive's
output IGBT's by breaking the link with the drive microcontroller. The safety
circuit uses only solid-state switches, therefore no feedback channel is required. If
needed, the PowerFlex 525 Safe Torque-Off status can be shown using one of the
normal relay outputs. When used in combination with a safety input device, the
system satisfies the requirements of EN ISO 13849 and EN62061 for Safe
Torque-Off and helps protect against restart. 
 PowerFlex 525 Relay Output Setup