hello, bricknuts!

I've never thought much about them until yesterday when I was reading some things about fuses. I've noticed that my volvo has two types of fuses, the glass tube types and the colored plastic types. regarding the colored plastic ones, I've noticed the metal strips vary in width from color to color, some are even concave in the center. in the past I've switched fuses, not considering much about the difference in width of the metal strips on the fuses. in fact, I've replaced some "skinny fuses" with the ones with a much wider metal strip thinking it's more effective and "newer." is there a reason for the difference in width of these metal strips on the colored plastic fuses? does the width signify where it goes in the fuse box? or it doesn't matter what colored fuse you put in each slot?