NOTE: at the time of writing this answer, the EF-relation was unclear (that was edited into the question after this was written). For correct approach with EF, check Mandeeps answer.

You can use the DateTime.Date property to perform a date-only comparison.

DateTime a = GetFirstDate();
DateTime b = GetSecondDate();

if (a.Date.Equals(b.Date))
{
    // the dates are equal
}