Difference between Sunfire Load Invarient & 300x2

The Sunfire Load Invarient Stereo amplifier is rated at 300w @ 8ohm, 600w @ 4ohm. Same as 300X2 (www.sunfire.com/pdf/600X2_300X2_manual.pdf). 300X2 has detachable power cord and slightly different layout. Other than this, what is the difference?

I guess some clarification is needed here.

Load Invariant Stereo amp refers to the older version which has a clean front plate. Whereas the 300X2 has "300 ~ two" on the front left corner and it's called "Super Definition Power Amp"...
Load Invariant Stereo amp is 250x2 and does not have a meter in the front, also is not bridgeable. I have 2 of these and they serve me well.