What is the Age Difference Between Earth & Jupiter? What is the age difference between Jupiter &amp; Earth?

Which planet was formed first, or were they formed at the same time?
It is generally thought that Jupiter "formed" first via the core accretion process. An icy core forms first and then sweeps up the gas around it. This process is generally thought to take from a few million to ten million years. After that, the solar system gas was dissipated and Jupiter was basically as it is today, but larger and hotter.

Earth formed on a longer timescale in the maelstrom of rocky planetesimals that made up the inner solar system. An essential part of the process was the collision that formed the moon, which probably occurred between 30 and 60 million years after the protosun began to form. Further heavy bombardment of the Earth that may have significantly changed its surface and atmosphere continued for some tens of millions of years after that.

The wikipedia page on planet formation in the solar system looks ok to me
https://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System
I may add some more academic references subsequently.