I think the biggest differences are:
- The Frances is the archetypical Camino. Several decades ago, it was commonly referred to as just "the
Camino de Santiago" because no one outside of a few academics and enthusiasts were aware that there were any others. If you read any books or watch any movies, etc. set on a Camino, chances are very good that it is the
Camino Frances they are set on. There is a much stronger feeling on the
Camino Frances that you are walking in the footsteps of millions of pilgrims over centuries before you.
- That said, there is certainly history behind the Portugues, as well. There are documented accounts of pilgrims right back into the middle ages.
- Both the
Camino Frances and the Camino Portugues have "Camino culture" (the community of pilgrims and a community of locals that support them). But some report that when walking the Camino Portugues Coastal in summer this culture is diluted by a lot of people who are there to enjoy the beaches and coast. I can't speak to this from personal experience, because I mostly walked the Central.
- The
Camino Frances takes you through more of Spain, through a greater variety of landscapes (mountains, plains, etc.) and of course regional cultural differences. On the other hand, on the Portugues from Porto, half your walk will be in Portugal, a completely different country.
- In the same vein, on the Frances you enter Galicia from the east and walk through cattle country. On the Portugues, you enter from the south and walk through wine country. Your nose will notice the difference.
- A crucial difference is that , for many people, the Frances is seen as an 800 km route, which can take 4-6 weeks to walk. On the other hand, many see the Portugues as a 2 week walk from Porto. For me, that would be what would mostly determine the choice of which to walk.
- Both have a lot of pilgrim supporting infrastructure (at least, after Porto on the Portugues), making them excellent choices for first time pilgrims or pilgrims with children.