How to differentiate between to select new fields e.g. Description

c.Description and lt.Description

DataTable lDt = new DataTable(); try {

        lDt.Columns.Add(new DataColumn("AreaTypeID", typeof(Int32)));
        lDt.Columns.Add(new DataColumn("CategoryRef", typeof(Int32)));
        lDt.Columns.Add(new DataColumn("Description", typeof(String)));
        lDt.Columns.Add(new DataColumn("CatDescription", typeof(String)));

        EzEagleDBDataContext lDc = new EzEagleDBDataContext();
        var lAreaType = (from lt in lDc.tbl_AreaTypes
                            join c in lDc.tbl_AreaCategories on lt.CategoryRef equals c.CategoryID
                            where lt.AreaTypeID== pTypeId
                            select new { lt.AreaTypeID, lt.Description, lt.CategoryRef, c.Description }).ToArray();

        for (int j = 0; j< lAreaType.Count; j++)
        {
            DataRow dr = lDt.NewRow();
            dr["AreaTypeID"] = lAreaType[j].LandmarkTypeID;
            dr["CategoryRef"] = lAreaType[j].CategoryRef;
            dr["Description"] = lAreaType[j].Description;
            dr["CatDescription"] = lAreaType[j].;
            lDt.Rows.Add(dr);
        }
    }
    catch (Exception ex)
    {
    }