Im a size 8 new look, but i cant fit into size 10 levis? ?

Hi, im a size 8/10 i normally buy my jeans from new look and theyre all perfect fit, today i went to buy some levi jeans and i picke up size 8 W 27 and they wouldnt go past my thighs, so i picked size 10 w28 and they wouldnt zip up and they still didnt fit, is there a different way levi works with their sizes? Pleasee helpppp x