The M4A1-S has a silencer that leaves no tracers to make it impossible for the enemy to see where the bullets are coming from when shooting through smokes. At the same time, the silencer takes away much of the noise when shooting which makes it hard to pinpoint the exact position. These abilities are what make the M4A1-S more stealthy as you can spray through smokes without the enemy knowing where you are standing.
From a first-person POV the M4A4 which leaves tracers every third bullet. Some players point to the fact that the visual cue you get when shooting makes it easier to transfer a spray onto multiple targets. Most pro players have automated their spray to a degree where they no longer need any visual cue to adjust their spray but instead rely on their muscle memory. It must be up to your personal preferences if you want to play with tracers or not.
If you want to disable tracers you can set r_drawtracers_firstperson into the console.
Fire rate and time to kill
The fire rate of the M4A4 is 11% higher than the M4A1-S. This only becomes an advantage when the first two bullets hit the head which is rarely the case.
The M4A1-S will often have a faster time to kill even with the slower fire rate. This is due to the significantly higher body shot damage. The time to kill is according to the CSGO weapon spreadsheet 0.30ms for the M4A1-s compared to 0.36ms for the M4A4.
With this information, we can conclude that the higher firerate can’t live up to the significantly higher body damage.
Accuracy and damage decrease by distance
The M4A1-S has slightly better accuracy when standing, crouching, and moving. Damage for the M4A1-S decreases by 6% for each 12.7m vs. 3% for the M4A4. The difference in damage decrease when fighting long-range is significant as shown below:
Damage against armor at a 2,5m distance
- M4A1-S: 26,27 dmg
- M4A4: 22,96 dmg
Damage against armor at a 76m distance
- M4A1-S: 18,30 dmg
- M4A4: 19,24 dmg
Across a 73,5m distance, the damage decreases by 5,65% for the M4A1-S compared to 16,2% for the MA4A. The significantly lower decrease in damage makes the MA41-S much more powerful at long-range fights.
There is no doubt that the M4A1-S is better than the M4A4.
Four body shot kills combined with the stealthy features, higher accuracy and lower damage decrease across distance makes the M4A1-S way overpowered compared to the M4A4. It doesn’t make sense that the most powerful CT weapon is the cheapest one.
The M4A4 might be more beneficial in close-range battles when only aiming for the head. Hopefully, we see more balance between the two weapons, so players have to make a choice towards the one that suits their playstyle the most. But for now, the M4A1-S would be the best choice in almost any case.