Generally, they have similar meanings, which is passage to another place. As far as I'm aware, the word 'voyage' is rarely used these days; it sounds incredibly formal as if you're embarking on an epic quest. The word 'journey' is more apt if you wish to convey a period of travel. The word itself implies LONG hours or distancel. For example, you cannot say "the journey from my house to my neighbour's house". Holiday or trip are the more 'colloquial' versions of saying that you have travelled somewhere.