Keep in mind that combs can be used across clipper brands! You can run the clipper with combs attached to get the hair down to a specific length, usually around an inch long or so and not even touch your scissors until you need to do some detail work. They are a huge time saver also for the fact that you won’t need to use your scissors as often. This means you won’t have to keep running over the same spot multiple times.
The stainless steel blades are thinner than the plastic ones so they separate the hair much more evenly. They attach more securely to the blade which means they won’t slip/move while you’re grooming your dog. This allows for more comfortable, more precise grooming sessions.
Honestly, if you have the opportunity, I recommend always picking the steel clipper combs for dogs.