This questions is answered by The Car Care Nut, an experienced Toyota and Lexus Master Diagnostic Technician, and his friend David Koichi Chao, an automotive engineer who has worked for Toyota for a long time.
The short answer is no. All the factories must meet the same standards. The same goes for all the manufacturers of all the parts and components, many of whom are owned by Toyota, the most important of those being Aichi and Denso, for instance.
If there are differences, the differences are mostly cosmetic and unrelated to reliability and quality.
