BX vs. OE 10/22 trigger housings

[unknwn]

Is there a difference between the original and BX trigger housings that could prevent use of parts from one into the other?
I came across a post somewhere that showed photo of a dramatic difference in the BX hammer (thicker across the pivot boss ?), that leads me to think that BX parts in an OE housing -might- be a problem, and if that's the case, the OE hammer in a BX housing might need spacers to keep the hammer properly centered.
Am I just wrong about this, or did I perceive the difference right?

 

[9x19]

The older trigger groups used a hammer with bushings on either side. The new trigger groups used a new-design hammer casting to eliminate the bushings.

Volquartsen probably sells more of their Target Hammers than others, and they simply started including a set of bushings, so their hammer can be easily installed in the new trigger groups. There isn't an internal dimensional difference between old and new that I've found, outside of manufacturing tolerances.