An "outing" has the idea of being fun, an amusement. It's the least common of the three.
A "journey" has the idea of being long. For me, and African safari would be a journey. If I were to take three weeks and explore more of my own country, that would be a journey.
A "trip" is the most versatile of the three. You can go on a trip for your vacation ("We made a trip to Disney World") or you can make a five-minute trip to the grocery store. In my experience, it's the most used of the three.
Do you want to write a couple sentences using them to see how they look?
[a writer, not a teacher]
Student or Learner