Fused versus un-fused shirt collars

[palmer]

As I understand the terms, a fused shit collar is one in which the exterior fabric is fused (by what means?) to the lining of the collar, and an un-fused collar in one in which the exterior fabric is stiched to lining only at the edges.

Is my understanding correct, and do you have any thoughts on the relative merits of either collar type?

Thanks.