Balk 8.05d, FED vs OBR
 

Do FED and OBR share the same wording for the balk rule 8.05d that deals with throwing to an unoccupied base with the exception of making a play?

Pretty much but the rule itself is a run-on-sentence that if you were in my 6th grade English class, you would not have been a friend of the teacher!

FED 6-2-4
ART. 4 ... Balk. If there is a runner or runners, any of the following acts by a
pitcher while he is touching the pitcher's plate is a balk:

b. failing to step with the non-pivot foot directly toward a base (occupied or
unoccupied) when throwing or feinting there in an attempt to put out, or
drive back a runner; or throwing or feinting to any unoccupied base when
it is not an attempt to put out or drive back a runner

Yes. Throwing to an unoccupied base except to make a play is a balk in all major codes. The purpose, as with all the balk rules, is to make defending against a steal somewhat more difficult.

No. OBR prohibits throwing to an uncoocupied base except to make a play.

FED prohibits throwing to an unoccupied base except to make a play OR drive back a runner.

Example: R1 only. Runner has large lead. F1 throws to second, R1 retreats to first. In OBR, balk. In FED, legal.

I may be wrong but I think accepted practice and interp of Fed is that R1 must be attempting to steal or feinting a steal.
If R1 only has a lead and throw goes to 2nd it's a balk.

Is a large lead a determining factor in your interp?
What is a large lead?
What if R1 does not retreat when F1 throws to 2nd, does it then become a balk?

I agree -- and a "large lead" is umpire judgment (just as it is in the "a play initiated by the offense does not cancel the right to appeal" rule)