Overall function wise they aren't all that different, especially if you're just using it for reading. Performance wise however the Nook Tab is much better, everything runs smoother.
In case you're looking to save a bit...
Overstock has Nook Color refurbs for $115 (1 year warranty)
http://www.overstock.com/Electronics...0/product.html
B&N has Nook Tab refurbs on eBay for a good price right now too
http://stores.ebay.com/Barnes-and-No...=p4634.c0.m322