A lock bracket works with small subtle forces. These forces cause the teeth to grow in the desired direction. The force is generated by the wire that runs through the locks. Therefore, the thread is often adjusted during the checks. With an outboard brace, the growth of the upper jaw is changed.
A block brace is a kind of fitness device for your lower jaw: it trains your muscles so that the jaw will hopefully grow more forward. The upper jaw can be widened with a jaw expander, which is also called "hyrax" or "spider".

Outboard bracket