Fw 189 A-1:
Initial production version, armed with two flexible 7.92 mm MG 15 machine guns in the dorsal and rear positions, one 7.92 mm (0.312 in) MG 17 machine gun in each wing root, plus four 50 kg (110 lb) bombs.
It could carry an Rb 20/30 or an Rb 50/30.

4 x Fw 189A-1S at factory awaiting delivery.

Fw 189 A-1/U2:
VIP transport version of the Fw 189 A-1.

Fw 189 A-1/U3:
VIP transport version of the Fw 189 A-1.

Fw 189 A-2:
The flexible MG 15s were replaced by twin-barrel 7.92 mm (0.312 in) MG 81Z.

Focke Wulf Fw 189A2.

Fw 189 A-4:
Light ground-attack version, armed with two 20 mm MG 151/20 cannons in each wing root, fitted with armour protection for the underside of the fuselage, engines and fuel tanks.

Fw 189 B-0:
Pre-production version of five-seat training aircraft. 3 built.

Focke Wulf Fw 189B-V5 (BQ+AZ) WNr 0010.

Fw 189C V1b:
Prototype of a heavily-armoured ground-attack, close-support aircraft. One aircraft

Fw 189C V6:
Prototype of a heavily-armoured ground-attack, close-support aircraft. One aircraft

Focke Wulf Fw 189B-V5 (BQ+AZ) WNr 0010.

Fw 189E:
Prototype only, powered by two 690 hp Gnome-Rhone 14M radial engines.

Focke Wulf Fw 189E.

Fw 189 F-2:
Fitted with electrically-operated landing gear, increased fuel capacity and additional armour plating, powered by two 600 PS (592 hp, 441 kW) Argus As 411 engines.

Sources:
Gunston, Bill & Wood, Tony - Hitler's Luftwaffe, 1977, Salamander Books Ltd., London
Wikipedia - Fw 189