I've found these definitions: A trip - a small casual outing from a day to a few weeks. A journey - a longer several months trip (in terms of time and/or distance), perhaps to multiple destinations, or with a greater sense of unknown. A journey may not be fully planned out ahead of time.
But for the journey I've also read that it doesn't matter how long it is, the emphasis is put on regularity. I still don't understand the difference.
The word "journey" conveys travelling a longer distance, over a longer span of time, perhaps with challenges or difficulties along the way. If I was walking across a continent, or circumnavigating the globe in a small boat, I might talk of taking a "journey".
The word "trip" can also be used to describe travelling long distances (I can take a trip from New York to Tokyo), but generally doesn't carry the same sense of being a long, arduous experience. And unlike "journey", the word "trip" can also be used to talk about travelling very short distances, like "I'm going to take a quick trip to the grocery store."
