Cisco RPS "sh env all" Need Output Explained?

I am having an issue with a power supply in one of my WS-C3560X-48T-L  When running a "sh env all or sh env power" on a similar switch I am receiving the following output.

Perimeter_3560_3#sh env all

FAN is OK

TEMPERATURE is OK

SW  PID                 Serial#     Status           Sys Pwr  PoE Pwr  Watts

--  ------------------  ----------  ---------------  -------  -------  -----

 1  Fixed                                            Good

SW  Status          RPS Name          RPS Serial#  RPS Port#

--  -------------   ----------------  -----------  ---------

1   Active          <>

Most of my switches show the PID as " Built-in". What is the significance between "Fixed" and Built-in" and if it is anything I should address?

Another example:

COLO_3560_24#sh env all

FAN is OK

TEMPERATURE is OK

SW  PID                 Serial#     Status           Sys Pwr  PoE Pwr  Watts

--  ------------------  ----------  ---------------  -------  -------  -----

 1  Built-in                                         Unavail

SW  Status          RPS Name          RPS Serial#  RPS Port#

--  -------------   ----------------  -----------  ---------

1   Active          <>

I'd say it's just different wording in different IOS versions. They might have updated it in IOS to support the new PowerStack features in the new WS-C3560X-48T-S  series switches.