Psychicanimal is correct that the construction of the two units is similar, and if you're unsure whether you'll be staying with vinyl long term, his advice to get something used and inexpensive is spot on.
However, if you're pretty sure you'll love vinyl and just want to get started, the NAD comes with an OEM Rega RB250 tonearm, which accounts for most of the price difference. The Rega is a far better arm to start than the Pro-ject, and is upgradable with all the RB250 tweaks. You could take it pretty far before you'd really feel the need to move way up the chain.