One Piece Chapter 547

[Augury]

I asked a specific question: "What is the difference between a logia and a paramecia fruit?"

Different paramecia fruits operate differently, and discussing certain paramecias' similarities to logia doesn't really answer the question. The rule Oda has used is:

Physical attacks pass through a logia user's body.
Physical attacks do not pass through a paramecia user's body.

Both paramecia and logia may be vulnerable to certain non-physical attacks that is dependent on each individual fruit.

The noted exception to this is Blackbeard, who states that his logia is different from other logia fruits because physical attacks do not pass through his body.

[The Chancellor]

Physical attacks pass through a logia user's body.
Physical attacks do not pass through a paramecia user's body.

That's another thing I didn't bring up. The fact that they have to pass through the users body and not do harm to them. Yeah blackbeard is one exception. I think he'll be the only one in the series though.

Another thing simply is, if you can find it naturally in nature then it's bound to become a logia fruit down the road in the series.

Although there are some I don't think we'll ever get:

rock
wood
water (although I think that Aokiji kind of took care of this one)
dirt?
lava (this might be another that's hard to tell because it's not really an element)

There are a lot of elements left. But I don't know whats to come. It should be interesting.