What's Better for Framing, S-P-F or SYP?

Southern Yellow Pine has a greater span capability than the mixed-species category "Spruce-Pine-Fir," according to Dr. Gene. January 11, 2007

I'm ordering a house from North Carolina, and they specified SYP, but they are substituting SPF. What will the difference be, other than cost?

Forum Responses
(Sawing and Drying Forum)
From contributor D:
I think that SYP refers to southern yellow pine, while SPF refers to spruce/pine/fir. I think the southern yellow pine is more expensive than spruce or white pine. Fir is probably a premium. I think SPF is cheaper as a category than SYP. I'm sure someone more knowledgeable than me will weigh in on this subject.

From contributor A:
Contributor D is right and on the money. You were shown the Caddy and got the Geo. SYP is a great building wood. One of the best for weight to strength and fastener holding. Did not know there was much white pine and fir/spruce in NC.

From contributor S:
SPF does not include Douglas fir (DFir), which is one of the best framing softwoods around. But for general framing, SPF should be fine. But you might want to ask for a discount!

From Professor Gene Wengert, forum technical advisor:
Where are they substituting SPF? If it is for the studs in the walls, no problem. If it is for joists and rafters, big difference. SPF cannot span the same distance as SYP, so you must have closer spacing, larger sized pieces (2x10 instead of 2x8, for example), etc. If the re-engineering is correct, the floors and roof will be fine with SPF. But if they used the same size members and same spacing for SPF as designed for SYP, you are getting less than you agreed to and will likely have very bouncy floors, etc. The analogy of being shown the Caddy and getting the Geo is correct. I would think that you are due a very large discount, and then I still worry about the floor bounce, or else you need to write a letter to the federal trade commission and expose these people for what they are. Potentially, this is a big problem and you need more info to assure you of the needed quality.

From contributor J:
Thank you all. The spec's were for SPF and they substituted the SPF for SYP, the better wood. The 2300 sq foot home goes up on the foundation in about 5 days. Then you finish the house like a regular home. Savings is in the labor.