Final answer:
The plum pudding model and the model of atomic structure used today differ in their structure and the discovery of the nucleus.
Step-by-step explanation:
The plum pudding model and the model of atomic structure used today have several differences.
Difference 1: Structure
In the plum pudding model, the atom was thought to be a uniform sphere of positive charge with electrons embedded throughout, similar to plums in a pudding or raisins in a fruit cake. However, the model of atomic structure used today, known as the nuclear model, consists of a small and dense positively charged nucleus surrounded by a cloud of electrons orbiting around it.
Difference 2: Discovery of the Nucleus
The plum pudding model did not have a concept of a nucleus. It was only after the discovery of the atomic nucleus by Ernest Rutherford through the gold foil experiment that the model of atomic structure used today was developed. Rutherford's experiment showed that most of the atom's mass and positive charge is concentrated in a tiny, dense nucleus.