2. A train and a plane
The same: They have passengers.
Different: The plane travels in the air, the train on the ground.
3. A holiday and a journey
The same: You can take your family.
Different: You go on holiday to relax, you go on journeys if you want an adventure.
4. A tourist and a traveller
The same: They travel around the world in different countries.
Different: A tourist may stay a couple of weeks in the specified country, a traveller would just visit the country, then carry on.