In Saiva Siddhanta, yogas are seen as progressive stages, not as separate yogas. So not all schools view yoga the same way. Swami Vivekenanada popularised the version you outline through his 4 books.
In Siddhanta, kriya yoga is synonymous with bhakti, or worship of the divine outside yourself. It is the second stage, with the first stage being seva, (karma yoga, or selfless service) . Raja yoga is meditation, or internalised worship of the divine, or searching for the Self. In Saiva Siddhanta, jnana yoga doesn't exist. it is just the state of jnanam which is the natural outcome of raja yoga, or deep meditation.
But there is great overlap, and they're not distinct. In a few hours, a bhaktar or a saint can do all 4. He might start with helping feed the poor around a temple. (seva) Then he could go worship the divine externally with a puja. (kriya or bhakti yoga) Then he goes and finds a quiet place within the temple to meditate. (raja yoga) At the end of that he attains a few seconds (or much longer if he's a saint) of jnana (bliss).
But this is just one explanation. many folks do separate them into 4 distinct paths, with jnana either being intellectual study of books, or a combination of that and meditating on the meaning.
So you'll get substantially different answer from various practitioners.
