Bolt or welded refers to the connection of the "toothed male-part" which is connected with your steering rod.
The "mother-part" is what you mount with the three screws on your wheel.
You can also use the 6hole lifeline hub since the "toothing" is the same (that is what lifeline told me).
So you could use a couple more wheels options.
Therefore if you buy a spare hub you can go for the welded, which is the cheaper version, cause you only need the "mother-part".
Sorry about my lack of technical english, but I hope you get the picture.
