What do you mean by trial? The content in the demo is the same as what a referral gets, but not the same as one of the 5 day buddy keys or 10 day guest passes, which have unlimited content, but timed played time.
The game content is the same as the demo, but referral accounts that purchase the game get a few additional bonuses designed to encourage teamplay during the first 30 days:
A special power to instantly travel to your friend (first 30 days).
A 5% Captain and Officer skill point bonus when you’re teamed up (first 15 days).
A 5% damage bonus when you’re teamed up (first 15 days).