From the Wiki
"Main article: Church of Silvanus
Silvanus had both clerics and druids in his faith, though their presence varied by location,[21] with druids being the more prominent due to his narrow focus on wild nature without concern for balance.[27][18][22] One could even find halfling druids revering him over their own pantheon's nature deity, though this was a rare occurrence.[40][41][note 2] Some barbarians,[42] hermits, wilderness dwellers,[4] and rangers also worshiped him.[4][43]
His clergy often worked together with the clergy of his allies, Mielikki and Eldath, towards common goals.[24][33][44] With the latter two being instructed to support, protect, and (if the need arose) obey the clergy of Silvanus.[44] These included protecting the wilderness from further encroachment by civilization,[4] such as the felling of trees and limiting farms or ranches to already cleared land. Also the fighting of diseases, planting new plants, and fighting those who did the bidding of Malar.[27][31]
His worship was widespread across the east and south of Tethyr, especially in the Forest of Tethir,[45] in the Dalelands,[46] the Moonshae Isles, the Chondalwood of the Vilhon Reach, and the Yuirwood in Aglarond.[30]"
Druids are not bound to a one god and arrive at their powers through different means. Even if we narrow it down to the clergy of Sylvanus in particular, the issue remains. Druids are extremists. Clerics get the work done.
From the Player's Handbook on the Nature Domain:
Gods of nature are as varied as the natural world itself; from inscrutable gods of the deep forests (such as Silvanus, Obad-Hai, Chislev, Balinor, and Pan) to friendly deities associated with particular springs and groves (such as Eldath). Druids revere nature as a whole and might serve one of these deities, practicing mysterious rites and reciting all-but-forgotten prayers in their own secret tongue. But many of these gods have clerics as well, champions who take a more active role in advancing the interests of a particular nature god. These clerics might hunt the evil monstrosities that despoil the woodlands, bless the harvest of the faithful, or wither the crops of those who anger their gods.
There is a fine line between a druid, a ranger, a nature cleric and an oath of the ancients paladin. One could question why so fine a line results in largely different spelllists and proficiencies, but I can't say there is no separation in lore.
