FERVENT stresses sincerity and steadiness of emotional warmth or zeal. fervent good wishes FERVID suggests warmly and spontaneously and often feverishly expressed emotion 영영사전인데 뚜렷한 차이를 못느끼겠는데요
fervid가 fervent 한 것 보다 좀 더 격하고 irrational?한 느낌이에요