There are two main factors that could be contributing here, the bezel teeth and the case material. The TC bezel teeth are more accurate for an older sub, maybe early '90s at latest but the later bezel teeth are sharper and catch the light better, giving more presence. The 904l case material also does make a difference despite what everyone on here wants to believe. If you have two subs, a rep in 316 and a gen in 904 both freshly washed, polished and untouched by human hands then yes, there will be little difference but as soon as you get your grubby mits on each piece the difference becomes apparent. The gen steel fends off scratches and holds it's brilliance much better than any rep steel can.
Gen crystals DO make a big difference but there are other factors like gasket height and rehaut depth and angle that will also play in.