What is the difference between a main breaker panel and a main lug panel?
Just so, what's the difference between a main lug and a main breaker?
Main lug panels do not have a main breaker. Instead the line wires run to lugs. The main breaker, which would function as the disconnect, may be located at the meter, or if the main lug panel is used as a sub-panel, it may be connected to the breaker at the main panel.
Also asked, do I need a main breaker in my panel?
If by distribution panel you mean main distribution panel then the only time you need a main breaker is when you have more than six handles. If this is a sub panel then the only time a main is required is again over six disconnects at a detached structure.
The biggest difference between a subpanel and a main panel is that the ground and neutral buses on a subpanel have to be separated. Most panels come with a bar joining the two, which is easily removed. Code requires subpanels to have a ground connection that's independent of the main panel's.