Fat content in chocolate chips
The second pack is a very slightly higher fat content, but as chocolate is cocoa solids+cocoa butter+sugar, we still can't be sure about the total cocoa content.

The melting point of cocoa butter isn't well defined, but two different dark chocolates will have a very similar melting point, so both will melt in baking, and solidify when the cookies cool.  

The solidifying behaviour of chocolate is interesting in that it cools to around body temperature while still liquid, than solidifies rather slowly, which is why it can seem cool but still be gooey in freshly baked cookies.

In the end, if you bake the cookies then serve them almost straight away, both will still be molten. If you let them cool fully, both will eventually solidify. In between, you can probably make more difference by serving them on a warm plate, or leaving them to cool in a warm kitchen rather than a cool living room.  The more expensive ones may end up nicer overall (on texture or flavour), but unless you want to arrange a blind taste test, there's no obvious reason to pay the extra.