Let me make it simple for those that have apparently not even used those features in either games.

The numbers mean are relative and made up.
In Halo 3 you had 20 options but you could do 100 different things with those options.
In Reach you have 10 options and can do 50 different things with those options, but there are multiple categories of those 10 options allowing a wider array of what you can do, but leaving less that you can do within those parameters.