Final answer:
The characteristics that lead to differences in viscosity among lava types are composition, temperature, and gas content.
Step-by-step explanation:
Differences in viscosity among lava types can be attributed to several characteristics, including composition, temperature, and gas content. Lava with a higher silica content tends to be more viscous, while lava with a lower silica content is more fluid. The temperature of the lava also plays a role, as hotter lava is generally less viscous. Additionally, the gas content in the lava affects its viscosity, with higher gas content leading to more explosive eruptions.