The drawings show where things go and how many. The specifications tell you what they are and how good they must be.
A drawing may show a door. The specification names the door material, the core, the finish, the acceptable manufacturers and the warranty.
Price from both. A takeoff from drawings alone misses required items such as testing, mock-ups, attic stock and extended warranties.
When the two disagree, do not pick the cheaper one in silence. Read the front end for the order of precedence. Then send an RFI or qualify your bid.