Are all bed frames the same?
In respect to this, do all headboards fit all bed frames?
Most headboards come with struts. These struts screw into the back of the headboard and will fit neatly on to the back of the any standard size divan bed. In most cases the headboard will include a gap on the standing frame which is where the bolts can be screwed in allowing for a sturdy head end which wont move about.
Also to know is, what is the difference between bed rails and bed frames?
It sounds like bed rails are just the sides of your bed frame, but they're actually a different product that you can buy separately to solve problems like lack of support, attaching a headboard or footboard to a frame with no brackets, or adapting a frame size to fit a different sized headboard.
Bed rails are made of solid angle iron. Side rails are approximately 76" long to accommodate normal twin, 3/4, and full size bedding. (Full size is also often called standard size, regular size, or double size. Learn more about bed sizes.)