Namaste Prabhat,
Yes, there is a difference. Aryas are what we strive to be. Vaidik Dharm is the path we follow. The Arya Samaj is the society we belong to. One can follow Vaidik Dharm and not be a member of the Arya Samaj.
_________________
Namaste,
Shishya
ॐ
ॐ सह नावतु । सह तौ भुनक्तु । सह वीर्यं करवावहै । तेजस्वि नावधीतमस्तु मा विद्विषावहै ॥
"Together may we be protected. Together may we be profited. Together may we do a hero's work. May we learn intelligently. May we never hate one another."
-Brihadaranyaka & Taittiriya Upanishads