Are both Gordonia and Bignonia from the same plant family?
no
Bignonia
Bignonia is a genus of flowering plants in the catalpa family, Bignoniaceae.
 Its genus and family were named after Jean-Paul Bignon by his protégé Joseph Pitton de Tournefort in 1694, and the genus was established as part of modern botanical nomenclature in 1753 by Carl Linnaeus.
Gordonia (plant)
Gordonia is a genus of flowering plants in the family Theaceae, related to "Franklinia", "Camellia" and "Stewartia".
 Of the roughly 40 species, all but two are native to southeast Asia in southern China, Taiwan and Indochina.
 The remaining species, "G. lasianthus" (Loblolly-bay), is native to southeast North America, from Virginia south to Florida and west to Louisiana; "G. fruticosa" is native to the tropical rainforests of Central and South America, from Costa Rica to Brazil.
Gordonia maingayi
Gordonia maingayi is a species of plant in the Theaceae family.
 It is a tree endemic to Peninsular Malaysia.
 It is threatened by habitat loss. Gondysia similis
The Gordonia Darkwing ("Gondysia similis", formerly "Dysgonia similis") is a moth of the Noctuidae family.
 It is found in North America, from North Carolina to Mississippi and Florida.
 The food plant occurs in Alabama and Mississippi and the moth could be expected from these areas as well. Gordonia singaporeana
Gordonia singaporeana is a species of plant in the Theaceae family.
 It is a tree found in Peninsular Malaysia and Singapore.
 It is threatened by habitat loss. Gordonia multinervis
Gordonia multinervis is a species of plant in the Theaceae family.
 It is a tree found in Peninsular Malaysia and Singapore.
 It is threatened by habitat loss. Gordonia scortechinii
Gordonia scortechinii is a species of plant in the Theaceae family.
 It is a tree endemic to Peninsular Malaysia.
 It is threatened by habitat loss. Gordonia penangensis
Gordonia penangensis is a species of plant in the Theaceae family.
 It is a tree found in Peninsular Malaysia and Singapore.
 It is threatened by habitat loss. Gordonia villosa
Gordonia villosa is a species of plant in the Theaceae family.
 It is endemic to Jamaica. Gordonia taipingensis
Gordonia taipingensis is a species of plant in the Theaceae family.
 It is a tree endemic to Peninsular Malaysia.
 It is threatened by habitat loss.