The difference between the 3/8" Tight-Lock Tiles and the 3/8" Sport-Lock Tiles is the manner in which they are designed. So the Tight-Lock Tiles come made as either a corner, border, or center tile, whereas the Sport-Lock Tiles come with removable edge pieces that allow you to turn them into a corner, border, or center. So if you are looking for a more consistent look to your floor, the Sport-Lock Tiles will give you that easier. If you are looking for a more seamless floor, then the Tight-Lock Tiles will give you that. Other than that, they perform the same.