D5100 vs D3100--Refurbished deals, what am I missing?

I am looking at getting my daughter a DSLR for Christmas--doing a bit of shipping on B&H I see a refurbished D3100 with 18-55 kit lens for $429, but also see a refurbished D5100 with an 18-55 kit lens for $429.  What am I missing here and why on earth would I buy a 3100 over a 5100?

Thanks for any advice/suggestions.