The word "yoga" comes from the Sanskrit root yuj, which means "to unite". Yoga means the union of the individual soul with the universal consciousness.
The ashtanga yog is a universal science for the seekers to follow a complete path for happiness & liberation.
Raj yog is a branch of yoga where a yogi practices control of mind by focussed concentration & rhythmic breathing.
Hatha yogi relies extensively on postures and asanas with different kriyas of breathing. It is about promoting the spiritual
Bhakti yog is path of devotion for almighty God. The followers project sincere and dedicated love for the "Ishwara".