Thank you very much for the feedback. Here are some additional pictures. This first picture is the same area at a different time of day and different sunlight;

The camera is making the transition more severe than the eye sees, but it is noticeable (And I believe the dark at the very far side is a reflection of the baseboard)

Also, I have read that red oak has more swirls and waves in it than does white oak. The next picture below shows the old area, and the second shows the new area. These are representative of the whole floor; its much easier to find swirls and waves in the old section, and there's some but very little in the new.

Can you comment? I'm trying to figure out - is this "Quarter-sawn vs Flat-Sawn, or is it Red Oak Vs White Oak"? Thanks!

Did you get a full sand/refinish on the old floor along with the new? Or did they leave the old finish in place and "hope" the new would match the old?

If they left the old finish in place then you could be seeing the difference between a clear coat (that does NOT amber) and an old solvent based finish that has a STRONG amber colour.

That would be the place to start. But I have a feeling this is red oak vs. white oak once again. Did you pay to have samples of your old floor sent off for identification to a lab? Should have cost you about $100 and taken 1-2 weeks to get the results back.

Please let us know a bit more about what was done and whether or not the old finish was left in place.

They sanded everything down - got rid of the old poly - old and new sections.

It's hard to tell from the pics but I'd say glennsfc is correct. The old and new wood seem to both have the light/dark stripes characteristic of White Oak. The new will probably blend better in time but a tinted coat of finish could make them closer now. Short of a chemical test, this site shows the best way to determine the type.

http://www.wood-database.com/wood-articles/distinguishing-red-oak-from-white-oak/

That's so far off. Has to red oak with new white oak.

Here's a tie in done with a 35 year old white oak floor and new. No difference in the color outcome.

Part of the difference is because the new floor has not been exposed to light as long. It will darken a bit. Even sanded, unless you sand off 1/8 an inch or more, there is a difference.

Also, quarter-sawn reflects light differently than plain sawn boards. I'm not sure why they thought they could

When you have the furniture back in and some rugs on the floor the difference will be minimal.

This is resolved. The contractor agrees that the new area does look different from the old area even though he originally told us it wouldn't. He stands by the old area being in white oak not red. He attributes the difference in appearance to quarter-sawn vs flat-sawn white oak. The resolution is he is going to replace part of the old flooring with quarter sawn, up to an appropriate dividing point between rooms, and share the cost with us.

Red Oak VS White Oak Flooring-How to tell

Thank You to everyone who commented - it was very helpful

Glad it worked out for you.