I can't speak to IELTS. I can tell you about ordinary conversation in US English.
"Trip" is a simple, plain word.
A "trip" can be any length. It can be a vacation or just an errand. It can take ten minutes or ten years. I am just about to make a quick trip to the library, on foot, to borrow a DVD. Last summer we took a trip to Yellowstone National Park. A song speaks of "a trip to the moon on gossamer wings." It's even possible to use it for a trip within a building: a trip to the bathroom.
A trip is a single event.
"Travel" refers to the general activity of taking trips. It often means more than one trip. It generally implies trips of many days and many miles, taken for pleasure or adventure. "Have you had a chance to travel, now that you're retired?" "Yes, we've taken trips to Canada, Alaska, and the Netherlands."
"Journey" is a somewhat literary word. It's used in writing, rarely in conversation. It carries the idea of some kind of big or important trip. You would never say "I made a journey to the supermarket." If someone said "I made a journey to Quintana Roo" I would expect to hear about off-road travel, indigenous peoples, discoveries of ruins. If they flew into Cancun and stayed at a big hotel, that's not a "journey."