I have Space Rangers 2: Reboot on steam. Does any one know how Space Rangers 2: Dominators on gog is different?

"Reboot" contains all of "Dominators" plus some extra ships, weapons, and equipment.

Reboot is an expansion to SR2: Dominators. Most places however don't sell it separately and instead offer it as standalone game (basically Reboot expansion preinstalled on SR2). If you have standalone Reboot (AFAIK, only impulse sells it as expansion. GamersGate, like steam, should really stop offering SR2 if they're not stocking Reboot expansion as only way to upgrade is to buy the standalone SR2:Reboot (basically forcing people to buy SR2 again to get expansion)), you don't need SR2: Dominators as it's included. Reboot added following:

• Five new text quests.
• 27 new planetary battle maps.
• 10 new hyperspace battle maps.
• More than 50 new governmental missions of different types to complete.
• New unique equipment.
• Two new game modes: text-quests and planetary battles.
• Improved galaxy searching system

Cool, Thanks!

In other words, it mostly more of the same stuff, which is great, but not necessary. It doesn't add any significant new features, but does make it much more replayable.

Listed Petrell changes not all.
Auto Translation with RuWiki
Also game has set of small improvements of game process:
Animation a mimicry of governors of planets movements of lips are expanded, traced;
Possibility to open the bank account under percent;
It is possible to release the prisoner, having brought pledge;
Probably to grant some sum of game money for supply of space bases by the weapon, the scanner and other equipment;
Search became more exact and informative;
Some pirates had cards with treasures on uninhabited planets;
The ship hold is expanded;
The majority of artifacts additional functions now have.

Reboot brings in game of less changes, than patches for original game.
Exists also not official addon under the name "Revolution", brings a lot of new, but only in russian language.
I don't speak english :-)

I got SR2 re-boot here in the UK via Amazon.co.uk for £7.99, so it was available at retail, at least in the UK. It only comes with a pdf manual, but it is more expansive.

Hey does anyone know if the impulse expansion works with the GoG SR2?

Just bought the expansion from impulse and upgraded SR2 from GoG. The Game runs fine and I've been playing for about an hour. Haven't encountered any problems so far.