Answer:
The difference between the Thompson's plum pudding model and the Rutherford atom model is the location of the electrons (option a).
Step-by-step explanation:
While Thompson compared his atom to a plum pudding, where the electrons floated freely in the pudding, Rutherford established the arrangement of the electrons in orbitals, which were found around the atomic nucleus like the planets around the sun.
Rutherford's findings also established the existence of a small, positively charged nucleus.
Thompson and Rutherford models did not differentiate between the charges of electrons and protons , overall charges or overall size of the atom.