Is the sangha in these 2 synonymous?
Tiratana (3 Jewels)
In the Tiratana Vandana, the Sangha is described as "attha purisa puggalā" which means the "eight kinds of individuals." So it is clear that the Sangha of the Tiratana is the Ariya Sangha.
Tisarana (3 Refuges)
In the Tisarana, there is no elaboration of who constitutes the Sangha. However, if we go by the precedent in the suttas, the lay people during the Buddha's time take refuge in the Buddha, the Dhamma and the Bhikkhu Sangha .
This can be found in the stock passage which forms the closing paragraph of many suttas such as the Aggi-Vacchagotta Sutta. Lokayatika Sutta, Abhaya Sutta, Cunda Sutta, etc where the layman, after the discourse by the Buddha concludes by taking refuge in the Buddha, Dhamma and Bhikkhu Sangha, with the verse "Esāhaṃ, bhante, bhagavantaṃ saraṇaṃ gacchāmi dhammañca bhikkhusaṅghañca. Upāsakaṃ maṃ bhagavā dhāretu ajjatagge pāṇupetaṃ saraṇaṃ gata nti." which is translated as "I go to the Blessed One for refuge, to the Dhamma, and to the Sangha of monks. May the Blessed One remember me as a lay follower who has gone to him for refuge, from this day forward, for life."