Plus de temps vs plus longtemps

Question

Is there any difference of meaning between "plus de temps" and "plus longtemps" ? Are both equally usual? Example:

• La pluie durera plus de temps que prévu.
• La pluie durera plus longtemps que prévu.

Answer 1

Both of your examples can be and are used without any significant difference in meaning although in theory, plus longtemps is longer than plus de temps.

There are a few cases where plus longtemps is not idiomatic or unused :

J'ai besoin de plus de temps.

*J'ai besoin de plus longtemps.