Santa means those in whose mind there always exists yoga of Brahma, those who always see and worship Brahma.
Two kinds of people can be SAdhu:
- Those who are indulged in sAdhanA of divya siddhi and are aiding their Guru are BrahmachAri SAdhu
- Grhastha who is means of sustaining this brahmachAri sAdhu class doing sAdhanA is also SAdhu
Those doing tapa in vana is called VaikhAnasa SAdhu.
Those doing sAdhanA of yoga as per Yati modus are called Yati SAdhu.
Rishi dhAtu means hinsA and gati. Because he gets vidyA, satya, tapa, shruti(shruti shAstra) from BrahmA so he is called Rishi.
When he achieves parama gati by perfecting nirvrtti he becomes Paramarshi(4 KumAra).
Rishi always appears by svayama. Rishi are mAnasaputra of BrahmA and they appear by themselves. They are not born and so they do not die but achieve moksha at end of their time due to their indulgence in nirvrtti marga. These are called Maharshi because they are focused on mahAna parAgati.
The mAnasa and aurasa children of these maharshi are called Rshi.
The children of these Rshi born through maithuna from womb are called Rsheeka.
Children of Rsheeka are called Rshiputra. They are called Shrutarshi because upon hearing from others they get Rshi-knowledge.
Mantra appear to these Rshi which delivers them from 5 troubles- asantosha, bhaya, duhkha, moha and shoka.
Thus 5 names of Rshi jAti are Paramarshi, Maharshi, Rshi, Rsheeka, Rshiputra.