There is some discussion about sannyasi and Yogi in Hindu scriptures..
Suka said, 'While living in the due observance of the duties of the
foremost of life, how should one, who seeks to attain to That which is
the highest object of knowledge, set one's soul on Yoga according to
the best of one's power?'
Vyasa said, "Having acquired (purity of conduct and body) by the
practice of the first two modes of life, viz., Brahmacharya and
domesticity, one should after that, set one's soul on Yoga in the
third mode of life. Listen now with concentrated attention to what
should be done for attaining to the highest object of acquisition!
Having subdued all faults of the mind and of heart by easy means in
the practice of the first three modes of life (viz., pupilage,
domesticity, and seclusion) one should pass into the most excellent
and the most eminent of all the modes, viz., Sannyasa or Renunciation.
Do thou thus pass thy days, having acquired that purity. Listen also
to me. One should, alone, and without anybody to assist him or bear
him company, practise Yoga for attaining to success (in respect of
one's highest object of acquisition). One who practises Yoga without
companionship, who beholds everything as a repetition of his own self,
and who never discards anything (in consequence of all things being
pervaded by the Universal Soul), never falls away from Emancipation.
Without keeping the sacrificial fires and without a fixed habitation,
such a person should enter a village for only begging his food. He
should betake himself to penances, with heart fixed on the Supreme.
Eating little and then even under proper regulations, he not eat more
than once a day. The other indications of a (religious) mendicant are
the human skull, shelter under trees, rags for wearing, solitude
unbroken by the companionship of any one, and indifference to all
creatures. That person into whom words enter like affrighted elephants
in a well, and from whom they never come back to the speaker, is fit
to lead this mode of life which has Emancipation for its object. The
mendicant (or Renouncer) should never take note of the evil acts of
any person. He should never hear what is said in dispraise of others.
Mahabharata Santi Parva Section CCXLV