Apparently everyone ignored my post

i believe in real life the m16 can be switched between single shot, burst and im not sure but maybe fully automatic
Spot on. Although I think some models were restricted to burst/single fire only. To increase accuracy of marines, and conserve ammunition.
If memory serves me correctly the burst only M16 was used initially during the Vietnam war as troops were fully-automatic blind firing. ¬¬ Don't quote me on that though, it may be that the only statement there that is true is that the M16 was used in Vietnam.
No, the only way you could fire in burst and full auto with M4 or M16 variants is to switch weapons
To clear up confusion. Some of the differences between the two weapons since some people were asking and others were making stuff up.
The M4 is shorter and lighter than the M16. And 80% of the weapons components are the same. In reality they both have fully automatic, semi automatic and fully automatic capabilities. They both use the same cartridge but the M16 has a slightly higher average RPM.
The firing mechanism and caliber rounds on both riffles are the same. So I assume considering everything in terms of power they are pretty much the same.
The M16 on CoD4 multiplayer was 'nerfed' as it would be overpowered. The statistics of CoD4 weapons rarely represent that of there real-life counterparts.
The first two sentences are correct, but everything else is wrong, look at my list of weapons of the M4 or M16 variety with firing options (@ bottom). The M16 has a slightly higher muzzle velocity than the M4 thanks to the longer barrel, and the multiplayer M16A4 is completely accurate in regard to its real life counterpart
Fire selection- all the models of both guns have a single shot ability, but after that: Full auto; M4A1, M16A2-3 round burst; M16, M16A1, M16A3, M16A4, M4
When I stated that they were not accurate I meant in terms of statistics. This means damage ratios when compared to other weapons, in real life the M16 doesn't deal much if any more damage than the M4.
If you noticed this statement 'In reality they both have fully automatic, semi automatic and fully automatic capabilities' referred to the M16 and M4 variants, not specific models. Both the M4 and M16 have models capable of single shot, burst and fully automatic. However yes as I also stated later down the burst first models are also incapable of automatic fire. This was implied when I referred to the model as 'burst only'
In accordance to several firearms sources my information seems correct, although the way I worded it may have caused your confusion, I suppose.