I was wondering if the FR20 uses the same tweeter and midrange driver as the FR30? I currently have a KEF Blade2 meta and know that it uses the same concentric driver as the larger Blade1 meta (which is too large for my room). Same is true for the FR30, it is as big as my previous speakers (Revel Salon2) and they were too tall for my taste in my 18x16.5x8 room.
Midrange and tweeter, yes, same.
Woofers are slightly different. @Chris_Brunhaver is the best person to describe differences in the woofers.
And, the FR30 has 2 additional rear firing tweeters.
It does make a difference, as you know.
I addition, when the FR30 was released it had one design of the tweeter. When the FR20 was released, it had a new version of the tweeter. After the release of the FR20 new FR30s were built with the newer tweeter. As @straightwire has the very first installed pair, I wonder which version of the tweeter he has?
I know these things because I heard Greg’s speakers in his tiny room. I fell in love with the FR30s and became a Chris B fanboy. I kept up to date on changes, up to a point.
I was told mine came with the new tweeters. Yeah 
Woofer design involves balancing three closely related factors: bass extension, enclosure volume, and sensitivity.
The FR20 uses half as many woofers as the FR30, so it has less total maximum output capability. However, each FR20 woofer has substantially more enclosure volume available to it. That additional volume allows each woofer to be more sensitive while maintaining approximately the same low-frequency extension and overall alignment.
To optimize the woofer for this larger volume, several parameters were changed:
-
The FR20 uses a lighter non-woven carbon-fiber and PMI-foam sandwich cone instead of the FR30’s aluminum cone.
-
It uses an aluminum voice-coil winding rather than copper, further reducing moving mass.
-
It uses a single spider instead of the FR30’s dual-spider arrangement.
-
The suspension is more compliant, or softer.
-
The FR20 woofer is 4 ohms rather than 8 ohms.
Because aluminum is less electrically conductive than copper, the aluminum wire must have a larger cross-sectional area. For the required impedance and coil geometry, this results in fewer turns and therefore lower motor force, or BL. The lower BL, lighter moving assembly, and softer suspension raise the woofer’s Q to the value needed for the larger enclosure.
The FR20 woofer therefore has greater sensitivity per driver while retaining similar bass extension. The FR30’s four woofers still provide greater total cone area, displacement capability, and maximum low-frequency output.
The two woofers share the same basic motor architecture and suspension profile, but the FR20 version is specifically optimized for its lighter cone, aluminum coil, single spider, lower impedance, and larger enclosure volume per woofer.
I hope this helps explain the differences.
What an awesome & complete answer! Thank you, Chris. So, what was your design goal for Qts for the FR30 & FR20?
Also, are the tweeter and midrange drivers the same units used in each speaker?
Did I read somewhere that you bought and own the FR20s?
Thanks
Paul