Block Mutations vs. Single Letter Mutations

Throughout chapter one of the book, Sean Carroll mentions two distinct ways in which mutations can arise (specifically p 33). A simple manner is single-letter mutations, where letter by letter genes are changed, creating different genes, creating different proteins, creating different phenotypes, creating selective advantages. Another mode by which genetic mutation can occur is by entire segments of genetic material relocating themselves within the genome, through transposition (in other words, these genes are transposons). We see this latter type in the development of the antifreeze gene, coding for proteins that prevent the icefishes' blood from freezing.
Given your knowledge of the various effects of different types of genetic mutations, discuss the possibilities and implications that follow with each type of mutation.