• Most advanced hull was the Floating Fortress (HH-A was the first raid prize. Researchable HH didn't come out until a few months later).
• No hull BPs.
• No special BPs.
• Only weapon BPs were the ones you found from salvages.
• No subs.
• No UAVs.
• No tactical modules.
• No drones.
• Only damage types were ballistic, penetrating and explosive.
• Only weapon types were cannons, missiles, rockets and mortars.
• No countermeasure weapons for ships.
• No Legion, Scourge or Reavers.
• No Uranium, Titanium or Base Parts.
• No FM.
• No R&D.
• No Mega Ships.
• No retrofit lab.
• No foundry.
• No repair specialists.
• No ship storage.
• No battle replay.
• No base defense fleet.
• No ship/target types. The concepts of skirmish, siege, conqueror, etc weren't introduced until years later.
• Any fleet could attack any other fleet.
• No way to increase missile range (Solid Fuel Boosters weren't researchable until later).
• Hardened Barrels 3 boosted ballistic range by 66% instead of 50%. Thus, Thuds with HB3 outranged everything and were practically unbeatable in FvF, especially on Sea Wolves.
• No gold (premium purchases were made using FB credits).
• No kixeye.com platform. The game had to be played through Facebook.
• No daily offers.
• No limited offers.
• Max Outpost level was 5.
• Max turret and wall level was 4.
• Max level for dock, labs and WHs was 10.
• Maximum storage for each resource was around 32 million.
• No tokens.
• No Relay Towers.
• 500 total sectors.
• Maximum travel distance was 1000 miles (or units or whatever) from your base. You could attack all of your own sector and maybe half of another sector but that was it.
• Fog of war or "black water" covered areas of the map you hadn't explored yet.
• Draconian bases weren't attackable.
• Resource mines, ranging from level 1-10, existed around Drac bases. After defeating the Draconian guard fleet, the mines would slowly fill your fleet with their resource. The higher the mine level, the faster it filled (level 10 mines could fill a FF fleet in around an hour). Draconians would periodically send fleets to attack you and reclaim the mine.
• You could only attack players within 5 levels of yourself. No FFA.
• It took far more experience to gain levels after level 20. 
• Current level 40 = old level 28
• Current level 50 = old level 32
• Current level 80 = old level 38
• Current level 100 = old level 40
• Current level 120 = old level 42
• You could only store one rocket in your launch pad at a time.
• Salvages were numbered 1-10. Level 8 salvages became the current level 40s and were fairly scarce due to very few people being high enough level to spawn them. Level 9s (51s) were extremely rare and level 10s (71s) were practically mythical.
• Opening high-level salvage without damage was extremely difficult and required a mix of mortars and missiles, lots of speed (16 mph minimum) and careful piloting.
• No rogue crews.
• No relocation (it was present in the early days but at the time in question, had been disabled due to bugs. It would be months before it came back).
• Ships still took weeks, even months to build. It would be years before the build time on hulls and components of this era would be reduced to what they are now.
• Buildings still took weeks to upgrade. Again, it would be years before the upgrade times for the levels available in this era would be reduced to what they are now.
• No world chat.
• No direct messaging.
• No alliances.
• Swag was the CM. Legends of his beard are still whispered in the night.

Dont forget:
Max travel distance was 800 and map speed was really slow.
Resources were hard to come by.
When your labs, shipyard or building upgrades were damaged in a base attack, you not only lost the repair time (which was considerable for the labs back then), but you also got time added to the build or research.
There was no standardization on raids. So you had to defend against everything and the raid was turned for a full fleet of last months prize.

Yes, it was fun back then, but a lot if the changes have been for the better.