Bios and cmos aren't the same thing. Resetting cmos doesn't necessarily mean a reset of bios, it only means a reset of temporary settings. There are multiple hidden and non user accessible settings contained in the bios, some of which will not get reset by resetting cmos. For instance a cpu voltage might have an acceptable range of 1.1-1.4v, but because of other settings changes might be at that 1.4v. Reset cmos and it'll load the 1.4v as already set and acceptable. Factory bios default would be 1.1v.
In most bios, F5 will load Optimized Factory Default settings and will include Every setting, both user accessible and hidden. There's no guarantee with a cmos reset or pc restart that that will happen. Only thing that will happen is a hard search of hardware and initialization of OS saved fresh drivers and paths.