The yoga of the Bhagavad Gita, if sincerely followed can provide a very good foundation for Sri Aurobindo’s Integral Yoga. It can lead to the state of Jivanmukta, free within despite the limitations of the mental, vital and physical instruments. The Yoga of Sri Aurobindo takes us beyond the state of Jivanmukta, the realisation of the Divine within, to a further transformation of nature, a conversion of the human mind into the Mind of Light, of human love into Divine Love, of human life into the Life Divine. Later there is a further transformation of the body itself into the Divine Body.
Of course by follower i mean someone who genuinely follows and puts into practice the teachings of the Gita or of Sri Aurobindo. If one is a non-practicing followers, that means someone who reads and believes but does not put into practice, then there may not be much of a difference.
Affectionately,
Alok Da