There is a good deal of overlap in meaning!
I'm going on a trip to Europe this summer. ['journey' could be used here, but not 'travel', in most cases.]
My journey will take me through six different countries. ['travels' would work here, and so would 'trip'.]
I love to show slides about my travels. ['trips' and 'journeys' could both work here.]
'Trip' is what we most often use.
'Journey' implies a longer or more adventurous trip.
'Travel' (often used in the plural) is a generic term for going off to some place for a while.
I've given the word that feels most natural to me in all three sample sentences.