Other than you can put them in an outside application. What is the advantage of paying more and using Porcelain tile ? Are there other advantages over ceramic tile? Since the porcelain is fired more and at a higher temp. ; I would think it is brittler.
Probably harder too. We have had some ceramic at the other house that is very soft - very easy to damage.
Porcelain tile is homogenous right thru so if it was a high traffic area or subject to gritty foot traffic, the appearance would last longer. In a shower application, since since it is denser, there is less chance of water wetting the substrate.
I don't know if there is any harm to ceramic tile installation indoors at a cabin/cottage if left to freeze during winter. I doubt its a problem.
For a cottage or cabin, I'd use ceramic tile. In our fancy washroom at home we used the too expensive porcelain.