I thought semaglutide was another type of insulin

When I first heard about semaglutide injections, I assumed they were basically another form of insulin because both are injections used in diabetes care.

After reading more, I realized they are described as different medicines, but I am still unclear about what actually separates them.

For people who have learned about both, how do you explain the difference between semaglutide and an insulin injection? Is the difference mainly how they work, who uses them, or what they are trying to achieve?