I'am getting ready to buy some lenses for basketball and am having trouble finding the difference between these two lenses seeing as one is $390 and the other is $500.
There is no difference. They are the same lens. You can't go by the photos and since Tamron currently only makes one version of this lens, it has to be the same.
The version without the AF motor in the body is the A09N.
Th version with the AF motor in the body is the A09NII.
Tamron began making the 28-75mm with the AF motor in the body in 2008. All current Tamron lenses have the AF motor in the body except the 180mm. I don't know when they stopped making the older A09N version, but I suspect it was also way back in 2008
The current Tamron Lenses have the AF motor built into the Lens.
Out of the two models you link, you will notice that the $500 model lists as one with a built in AF motor and I believe that is what makes it different.
A few years ago, Nikon decided to no longer have the AF motor built into all their cameras and instead, to incorporate it into the lens itself. This also meant that independent lens manufacturers such as Tamron and Sigma had to produce their Nikon lenses with the AF motor built in.
Today, Nikon DSLR’s that do not have a in-built AF motor are; D40, D60, D3000 Series and the D5000 Series. They will therefore require a lens that has the AF motor.
Nikon DSLR’s that still have the AF motor incorporated into the body are, D50/70/80/90/100, D200-300, D7000, D600/700/800 and the D1,D2,D3,D4 Pro models and related models D2H, D2X, D2Xs, D2Hs, D3X, D3S.
One other thing to notice, when Tamron changed their lens to incorporate the AF Motor, they never changed the actual part number and this in the UK lead to a lot of confusion until the older non AF motor Model was taken off the shelves and officially discontinued
Hope this helps