I saw on E-Bay a 2007 Lionel Macy’s boxcar. Is this the same boxcar from last year? Are they making a different one each year? If it is new, how can I tell the difference between last years car?
Assuming I found the same auction as you, (I only found one for a Macy’s Lionel boxcar with “2007” in the description) it’s the same car.
The only difference would likely be the price sticker Macy’s put on the back of the orange box for cars sold in Macy’s last year. Obviously, cars shipped to Lionel dealers would not have this. I would also suspect perhaps there is not a single car sized shipping carton this year, as once this became regular production, they probably would do a more standard 3 per case configuration.
The item # is the same (6-25043). Lionel put this car in their January 2007 catalog.
Also, you can bet that if it were a new uncataloged car that wasn’t widely known about yet, it would not have a “buy it now” of 39.99. 
Hope this helped
I have that pre-ordered from the 2007 Volume I catalog.
What will make this interesting is that there were a number of this car made for last year’s Macy’s parade in conjunction with Lionel’s launch of Lionel returning in a big way to Macy’s flagship NYC store. The cars from last year have a stamping on the door that says “25043 BUILT 2006 BY LIONEL” (I have one). So if the 2007 version is stamped built 2007, it will distinguish the 2 cars, but with the same model/product number.
I haven’t compared the two cars but, the 2007 version is labled on the shipping over carton “shipped 6/23/07” I might be mistaken on the exact date in June. Had a customer/collector ask for one to be put aside in the overcarton with the June date.