WEll Allah knows the best ke muslim and momin main se zyada haqdaar kon hai jannat ka, but Quran tells that jannat is made for momins.
and as u asked wats the diff between muslim and momin... simple muslim is a person like us who is just muslim coz he was born in muslim family, he believes in islam but pratices it once in a while. on the other hand momin is a person who is muslim coz he had research on islam and he really pratices islam in his daily life.
but every muslim is supose to bcome a momin
**muslim = the person who submits (by dictionary)