Hi, Total. Studs are placed every 16" on centers. That means that there should be a 14-1/2" opening between them since a 2x4 is actually 1-1/2" thick. This is the same for inside or outside walls. The reason for that is that sheet goods like plywood and drywall are 48" x 96" and the 16" divides evenly into these dimensions. Differences arise around window and door openings and to fill in the space where the length of a wall doesn't divide evenly as in a 10' long wall with 4' wide or 8' long panels. Roof joists are different, by the way.
Your blueprints shold have at least the suggestion of framing locations. And your contractor or architect should be able to explain to you any differences. Your local building inspector has to sign off on the rough carpentry also. If you choose to question them, don't forget that the crew is working by the hour. And don't ask Jay J if you can help--like in the Certainteed commercial--since he has to get back to this board.