"实在" can be an adj, means honest, 他是个实在的人(he is an honest man), and "实在" also can be used as an adv, "really",我实在抱歉(I am really sorry).
“真” is used widely as an adj, means real,ture, veritable or even original...这是真的,不是赝品(it is original,not an imitation), 这件事是真的(this is true). "真" is similar to "实在" in adv,我真抱歉(我实在抱歉)真地
我真的实在很抱歉(I am really really sorry),both are adv
他是真的实在(he is really honest), 真is adv,实在 is adj,