lens - Why is the Nikon 70-300mm f/4.5-5.6G ED IF AF-S VR twice as costly as Nikon 55-300mm f/4.5-5.6G ED VR AF-S DX?

The Nikon 70-300mm f/4.5-5.6G ED IF AF-S VR is almost twice as costly as Nikon 55-300mm f/4.5-5.6G ED VR AF-S DX. Why is that so?

The only difference I see is the internal Focus. If that ignored are there any other differences between the two in terms of clarity. I was wondering if the 70-300 is worth all that extra money just for the IF!

Amazon links below

Nikon 70-300

Nikon 55-300

Answer

The 70-300 is a full frame (FX) lens, the 55-300 is APS-C (DX).