The main difference between the bank guarantee formats ICC 458 and ICC 758 lies in their intended use and the specifics of their provisions. ICC 458, which is related to guarantees in international trade, emphasizes the conditions under which banks must pay on demand, while ICC 758, which pertains to standby letters of credit, offers broader flexibility in terms of the obligations and documentation needed. Additionally, ICC 758 allows for more complex structures and may incorporate additional terms, making it more suitable for a variety of financial transactions. Overall, ICC 758 is often viewed as more comprehensive compared to ICC 458.