Jnana Yoga - union by knowledge
Bhakti Yoga - union by love
Karma Yoga - union by service
Mantra Yoga - union by speech
Raja Yoga - union by mental control
Hatha Yoga - union by bodily control
Jnana is the path of knowledge or wisdom, specifically liberating knowledge or intuition. It concentrates on discerning the real from the unreal or illusory.
Bhakti is the path of devotion, the method of attaining God through love. AS with other yoga paths, the goal of the Bhakta, the devotee of God, is to attain oneness with the Diving. This is the yoga of selfless love, compassion, humility purity and serious intention to merge with God.
Karma yoga is the yoga of service; specifically, Karma yoga is the path of dedicated work without thinking of personal reward. Karma is both action and the result of action. What we experience today is the result of our karma - both good and bad - created by our previous actions.
Mantra yoga is the yoga of speech or sound. Mantra yoga uses different mantras as an integral part of the practice. The most well known and the most important mantra is 'Aum'.
Raja yoga is the yoga of mastering the mind. The basic premise of Raja yoga is that our perception of the divine self is obscured by the disturbances of the mind. If the mind can be made still and pure through repeated practice we can make the mind our servant rather than being its victim.
Hatha yoga is the yoga of bodily control, including asanas, kriyas (cleansing processes with water ad cloths), pranayamas (these maintain and channel the flow of energy through the breath), bandhas (closing actions that prevent energy loss).