The closest Sanko to the Jescar Warmoth sells as 6105 would be SBB-214 the width 2.4mm height 1.2mm
6105 is a Dunlop designation.
Dunlop Width: 2.36 mm Height: 1.50 mm the closest Sanko is SBB-214H width 2.4mm height 1.3mm.
So dimensionally there is no significant difference between the wire. What you are noticing however is that your Warmoth frets have not been levelled, dressed, crowned and polished whereas the Fender has and hence the difference in appearance and slightly no doubt in size.