Here is a post I put up on Piquet Facebook page outlining changes I had noted from V2 to V3.
I did try the V3 rules using PDF (yuuckk) as still waiting for Rules & cards here in UK
Couple of relevant posts on my Blog
sgtsteiner.blogspot.com
"FOB 3 changes from FOB 2
Herewith a brief list of changes I have noted from FOB2 to FOB3 showing a substantial number of major and minor changes/tweaks.
They are in no specific order and only outlined (as don't want to spoil anyone else's reading fun!).
There may be some I have missed or am in error over detail (so feel free to add to list/expand info)
Also not mentioned is Seasons of Battle as new to most everyone (but a lot of changes from an early playtest set I tried)
Order and Disorder replaces In and Out of Command (semantic change)
Changes to card deck which are now a basic 23 cards not 27.
Only 3 Deck quality types now with correspondingly only 1-3 Lulls cards.
Manoeuvre card is gone with its function now included on Leadership card (but not possible if Leader rolls 1 on Rally attempts which must occur first)
Infantry & Artillery Firepower cards renamed as Fire cards (functionally the same)
Rapid and Rolling Fire cards appear for Breach loaders/MGs etc
Special Event card definitions expanded
A new Incident card appears with lots of scenario options (replacing some special cards in FOB2)
Rally from Routing now achieved by rolling higher does not require having to recover 1UI
Daring Deeds – Officers can now assist Rallies by upping Rally dice by 1-3 but this puts them at immediate and corresponding risk (you add 3 so you die on a 1-4 on D12)
Officer Replacements – slight tweak in that Replacement may be delayed on a roll of 1-2 and their Quality is rolled for instead of automatically down 1 dice level.
Units can only Change Facing or Formation not both per Move Segment or on Leadership card
Unit Integrity has been amended, all types now destroyed on reaching zero (previously it was Rout on zero and destroyed on -1) also Cavalry now 4UI and Artillery 3UI.
Cavalry no longer Destroy units when they cause 2UI and Even win, this is now Rout result.
Attack Columns do not suffer Down 1 from enemy musketry only from Artillery
Certain units (Skirmishers and Cavalry charged by Inf) can Evade but may or may not become Disordered (DD vs DD)
Skirmish rules tweaked to encourage them to hug terrain (extra Down 1 firing in open)
Grand Batteries redefined acting as separate Commands with only outside in a line of units able to turn to amend facing.
Terrain in general has had several tweaks with Hedges and Walls now treated as separate features.
Bridges and suchlike now must be taken by Columns ‘Forcing Passage'
Interpenetration has been redefined and restricted (especially by period) and no charging through into contact.
Pursuit has been changed (user defines those types subject) with pursuing units losing same UI as defeated unit.
Lots of Period Specific Army lists (seem to be more than in FOB2?) with English Civil War making a new appearance with quite a few new troop types, formations, special rules.
Lots of defining by period what troop types can or cannot Immediate Melee and suchlike.
Several separate Period specific Quick Reference sheets.
These include several changes to the old generic FOB2 sheet.
Some include entries for Cav vs Inf and suchlike"