"Map My Run" vs. MFP and Daily Caloric Intake

I downloaded the app "map my run" to my phone to track the distance I walk. After putting my stats in the app it suggested my daily caloric intake should be a little over 1000 calories a day... 300 calories less than MFP recommendations. I understand these sites are just for reference, every person is different; but still, this is quite a bit of difference (30%) between the two apps... any thoughts?