Travel is usually a verb. As a noun, it's usually uncountable, and is an abstract concept. For example, 'Travel broadens the mind'. By contrast, 'journey' and 'trip' are countable nouns referring to specific events. A journey is what you do when you travel from point A to point B. A trip is similar, but often shorter. A trip can also refer to the whole holiday/vacation itself - in other words, the time spent travelling and also the time spent at the destination and the journey home e.g. a business trip. These words have exactly the same meaning in the real world as they do on the IELTS paper. IELTS is an important exam, but it doesn't have its own meanings!

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."

All these words have differences in the length and duration of the action. travel = something that you want to go usually much longer than a trip trip = a very short travel journey = much longer and arduous trip, usually with a planned purpose and can be made up of many trips etc. I took a trip to the beach. You don't say I took a journey to the beach. I travelled to the beach implies you live hundreds of miles away from it. In ELTS, they want to know if you understand the different subtleness of the words. Another example... I took a trip to the Temple of the Sun. -- Either you live closeby or took a vacation there. I journeyed to the Temple of the Sun. -- Definitely from a long distance and duration with a purpose I travelled to the Temple of the Sun. -- The distance is long and so is the duration but can be on a vacation or not.