Well 88 % vs 70 % or even 60 % will not make a huge difference as long as the active ingredient purity is fine.
This is the critical point : is gV's active ingredient as pure as Vascepa's ? I guess it must be NLT 96 % in terms of fatty acid esters content but is it totally free of DHA as Vascepa is ? Or some trace in it ?
I suppose Amarin is going to make the proper analysis asap..