Those Efest 2100mAh button tops are likely to be like these: Efest IMR18650 2100mAh (Purple) 2017

Efest can print whatever they like on their wraps, but they're consumer oriented number bloaters.

Samsung is rating conservative and aims for cycle life. Set the 30Q and the above Efest in the comparator and you'll see how the actual voltage output difference is really tight at first, to shortly after come in 30Qs favour due to energy density.

30Qs can also be pulsed safely at 30A but temperature monitoring is required.

Cheers ^:)