The amount of factories on a planet, economy starbases, asteroid mines, your total spending for production and how much of it is allocated for military (shipbuilding) and social (improvement building) production.
The high end factories provide a lot of Manufacturing Points (MP), but take very long to build and have a very high maintenance cost. It is better to build several lower end factories. This is more cost effective, in both time to build and maintenance.
You can use economy starbases and fit them out with production assist modules. They effect both manufacturing and research on all of your planets in the area of effect. Several starbases stack, but you can have only four in one sector. You only pay for half of the bonus production you receive that way, but it takes time and money to build the starbases.
Asteroid mines act like factories, but with several differences. The mine provides additional MPs for a planet. You can change which planet receives the MPs, but the more distance between the two, the less MPs arrive at the planet. You don't pay any maintenance for the mines, and while the early ones are build up quite fast, it takes very long to build the more advanced ones.
The total production slider regulates how much of your overall production capacity is used. The other three regulate in which areas it is used. If you want to build ships faster, crank up the military slider. If you want to construct buildings faster, crank up the social slider. The same goes for research. In some cases, you want a few planets to do something specific. For example, while your other planets are improving their infrastructure, you want one to quickly build ships. In that case, you can set that planet to focus on military production. There is a check-box for that on the colony management screen in each of the three production areas. The focus essentially takes away production from the other two areas and increases the one in which you want to focus. I'm not entirely sure of the numbers, but I think it takes 25% of the other two and increases the one to focus in by 20%. Also in keep in mind, that unused social production is transfered to military production, but not vice versa.
Hope this helps.
