lateral_friction explanation

[kYamek]

While working in pyBullet, and using URDFs, the implementation of friction is a bit confusing. There are several URDF values such as "lateral_friction" that when changed between 0 and 1 for a block sliding on a plane, make no impact on the physics I am trying to simulate. How does lateral_friction relate to static or kinetic friction? Additionally, with two URDFs interacting, we have to separate URDFs, should the lateral_friction values match in order to recreate accurate friction coefficients?

Bonus question is about mass value, and how changing it doesn't affect the physics either.

Thanks!
Kyle