In the picture, the coin on the right has an unusual depiction of the captive. Normally the captive is kneeling and the coin on the left shows a typical portrayal of the kneeling captive. The coin on the right has a small captive standing up. Just artistic license on the engraver's part, but I found it interesting...plus it's nice when something breaks up the monotony of this common type.
Valens
A.D. 364- 367
18mm 1.6gm
DN VALEN-S PF AVG, pearl-diademed, draped and cuirassed bust right
GLORIA ROMANORVM Emperor advancing right dragging captive with right hand and holding labarum inscribed with Chi-Rho
In ex. R dot TERTIA
RIC IX Rome 15b, type xi(b)