The difference in gear score is between the peacoat being epic while the shirt is still common. Once you rank up the shirt at the upgrade bench three times, the level will be properly impressive.
However, you probably only want to upgrade it twice (to blue), and save the epic upgrades for material crafted with higher tier cloth/leather. A blue set with T3 materials will get you into the ascended realms to harvest T4 and T5 materials.
The difference in gear score is between the peacoat being epic while the shirt is still common. Once you rank up the shirt at the upgrade bench three times, the level will be properly impressive.
However, you probably only want to upgrade it twice (to blue), and save the epic upgrades for material crafted with higher tier cloth/leather. A blue set with T3 materials will get you into the ascended realms to harvest T4 and T5 materials.