Under standard conditions, neopentane is a gas while n-pentane is a liquid.
Given that both are non-polar and have identical chemical formulas (C5H12), the reason that n-pentane has a higher boiling point is that
1. it has more H-bonding than the neopentane.
2. it has more C-H bonds that are slightly polar.
3. its straight-chain structure allows for a substantial permanent dipole.
4. its straight-chain structure allows the molecules to have more instantaneous dipoles interacting at close distances.
5. n-pentane has more valence electrons and therefore can form more instantaneous dipoles.