- The Romulans who no more look like Vulcans.
- In TOS and TOS movies, we saw the Vulcan coquetry and sensuality. Since TNG, the passionnate Romulans are beiger than the cold TOS Vulcans.
- In TOS, the "blue division" was active, we oftenly saw geologists, anthropologists, physicists, sociologists, biologists, etc... I suppose the fact Data's make-up didn't fit with the blue uniform didn't help, but TNG is also the take-over by the engineering. A lot of issues are not treated by the engineers. Being a specialist on the Enterprise-D means you're an engine or deflector specialist.
- In TNG, the civilians seems to be always government officials or scientist working for institutions. We don't seen many "independant" civilians in space or purely civilians ships.
- For me the worst case: The Prime Directive. In TOS, people who broke the PD were Ronald Tracey or R.M. Merik. In The Paradise Syndrome, nobody said saving the people from the alien planet was against the Prime Directive. It had concrecte goals: avoiding imperialism and other ism. In TNG, the Prime Directive is about abstract ideas. For Picard, cultural contamination is worse than letting people dying.