These are 2 'Polo' shirts.
This means they are made of a different fabric from a tee. It's coarser, with a bit of texture. They also have 1 not-that-useful button & a foldy type collar. What it also means? That each one costs a lot more: These are 40 dollars each.
The Sonic element is small. The Tails shirt is gray with a small, all-embroidery 'sideways facing' Tails face on the upper right chest side. The Sonic one is black (or dark charcoal) with the traditional 2/3 faceing classic face in the same spot, also in all-embroidery.

These are both Sega Shop items in 2018. (But they seem a little expensive, unless maybe 'polo' fabric doesn't wear out? The embroidery is nice though, and since the designs are small, they're an ok way to bring in Subtle Sonic)