Not a stupid question. Improved electrical system, beefed up suspension, improved Duke system, to name a few. All documented in my walk around. The easiest external giveaway is the new, more robust towing points front and rear.
Or, as I see someone else is busy typing away at this very moment - you could Google it. 
The Bradley M2A4 is an upgraded version of the M2 Bradly Infantry Fighting Vehicle (IFV) with improvements in powertrain and suspension to handle increased armor and advanced technologies. It features enhanced armor for greater protection, improved survivability, and upgraded electronics for better communication, situational awareness, and targeting capabilities. These upgrades ensure the M2A4 remains effective in modern combat scenarios while maintaining the original role of transporting infantry and providing firepower.
The A4 version Brad is laid out with pics of the differences here:
M2/M3 Bradley Reference - Reference by Subject - KitMaker Network
No, that is an M2A2 ODS SA which is the type sent to Ukraine. It is an upgraded A2 with most A3 features minus the CITV on the right rear of the turret.
Ukraine M2A2 ODS SA - M2/M3 Bradley Reference - Reference by Subject - KitMaker Network
Also available from Magic Factory
Ich melde mich wenn ich den Bausatz auf dem Tisch liegen habe. 
Duke emitter
I’m still waiting for the BFIST Bradley from Magic Factory 
That is the idea with the camo, have it blend in to its surroundings, not stand out because it is too bright. Many modelers paint more on the artistic side making their model stand out more than reality.
Its fresh paint. Give it a little time.
I’m happy to report that they’ve finally added the necessary components to the turret basket, save one. A nice improvement over previous versions. Now if they could add them retro-actively.
Not in a hurry to build this one, however.
