Bhakti yoga, the yoga of love and devotion. A devout Christian, for example, who loves Jesus with all his/her heart, would be considered a bhakti yogi. A devout Hindu whose devotion to his/her guru (teacher) would also be a bhakti yogi as would be a mother whose devotion to her children overreaches her love of self, or a wife who gives all to her husband, or an orthodox Jew whose life is devoted to love of the unfathomable Lord.
Japa yoga is a way of reaching connection through chanting holy names or songs of praise. A gospel Christian who sings out his/her love of Jesus would be practicing japa yoga, as would a Bhuddist monk who chants to the vast void before silent meditation. A Rastafarian who sings out to his Jah is practicing japa yoga. I would contend that in his own way, the wild northern wolf, howling at the midnight moon is also practicing japa yoga.
Karma yoga has to do with reaching this sense of connection through good deeds and ceremony. A karma yogi or yogini might be devoting hours each week doing charity, serving the homeless on thanksgiving, or chaining him/herself to a thousand year old redwood that is about to be destroyed in honor of the almighty dollar. A Karma yogi/yogini may have a separate meditation space in his/her home, and each morning, cut a rose and place it in a vase by the eastern window to greet the new day. A Catholic nun, whose day begins, ends and is in all ways a life of ceremony and service, would be considered a karma yogini, as would be a Muslim who prays 5 times each day at the appointed time.
Jnana yoga has to do with the mind. It is the path of the intellectual. A janana yogi/yogini reaches that sense of connection through study and the reading of holy scriptures. An orthodox Jew, for example, who studies the Talmud, who has, since he was three years old, devoted his life to this study, is immersed in jnana yoga. A Hindu who studies the Upanishads, the Vedas etc., the holy writings of India is practicing janana yoga. I would contend that the aetheist, studying philosophy of the ages, is in his/her way, practicing jnana yoga.
Raja yoga: Raja (King’s) yoga is by some considered the highest yoga. It is the yoga of meditation and has to do with gaining the sense of connection through silencing the mind’s chatter until the practitioner sees beyond individual isolation to universal oneness. Silent prayer (when it is not about requests for physical gain) is a form of Raja yoga, as is sitting meditation in whatever tradition it is practiced.And, in fact, just as sitting still for hours on end can serve to bring one beyond the individual sense to the sense of the universal; its opposite, dancing, as seen in the practices of many native American tribes, or in the eastern world sufis, or in Western traditions, of Hasidic Jews, can do so as well. In fact, hatha yoga, the physical exercise so popular nowadays in our western world is a form of raja yoga, a meditation or prayer of the body: