I’ve been a lil hazy on details, what’s the difference between the Spartan 3s and Spartan 4s? Sources?
I’d say, go and halowiki it. It will explain it better than any forum member will.
Well your best sources are the various Halo wikis.
So, basically 3’s were like 2’s in that they were abducted from their homes and conscripted into military duty. Only the 3’s were taken from a wider gene pool than 2’s because augmentation technology had been refined over time. 3’s were equipped with spi suits because mjolnir suits would be too expensive to make for the hundreds of spartan 3’s. 3’s in exchange for the sub-par equipment had a more rigorous training and special augmentations that allowed them to have a boost in adrenaline when close to death. 3’s were most intended for suicide missions and were not flaunted around by ONI as propaganda to keep with spartans never dying theme.
4’s on the other hand were voluntary marines and ODSTs who had survived the human-covenant war. Their augmentations were not as effective as those given to 2’s and 3’s due to the fact that they were already aged, but in return were outfitted with the GEN-2 mjolnir suits, which brought their reflexes up to par with a spartan 2 in GEN-1 mjolnir armor. Spartan 4’s are more well known to the public now as spartan 2’s and 3’s are mostly dead.
That’s about all I can think of on the surface, anyone feel free to correct me or add on.
Shifting this to Universe so the canon kids can answer you. 
S-III’s are essentially S-II’s with better training, they have the same augmentations as the II’s etc. Only a handful of S-III’s were given MJOLNIR (mainly the CAT-2’s, who are S-III’s who matched the S-II genetic profile) because of budgetary reasons.
S-IV’s are recruited as consenting adults from the military and given augmentations (which are weaker than the previous two generations) and GEN2 MJOLNIR (which makes up for the weaker augs).
This is a really nutshell version, but it explains it pretty well.
So do the 4s have any augmentations or body enhancements? Cause look at the 4s and they all stand big and tall
Also I’m on Halo App cause net surfing eats away my data
> 2533274859436467;6:
> So do the 4s have any augmentations or body enhancements? Cause look at the 4s and they all stand big and tall
They do have augmentations, but they aren’t as extreme because the IV’s are already adults. This is compensated because the GEN2 MJOLNIR boosts their strength and things more than the GEN1 armor.
As for the S-IV height, if I’m not mistaken the S-IV’s have their bones lengthened during augmentations to make them taller.
> 2533274859436467;6:
> So do the 4s have any augmentations or body enhancements? Cause look at the 4s and they all stand big and tall
Yes, they still do have augmentations, just not ones that affect them as drastically, because they have already grown.
> 2533274820430915;5:
> S-III’s are essentially S-II’s with better training, they have the same augmentations as the II’s etc. Only a handful of S-III’s were given MJOLNIR (mainly the CAT-2’s, who are S-III’s who matched the S-II genetic profile) because of budgetary reasons.
>
> S-IV’s are recruited as consenting adults from the military and given augmentations (which are weaker than the previous two generations) and GEN2 MJOLNIR (which makes up for the weaker augs).
>
> This is a really nutshell version, but it explains it pretty well.
Holy -Yoink- a person that actually understands the canon about S3s, I was going to give up because of the S2 fanboys bull -Yoink- I read for years but the fact that some people understand that S2 and S3 are equal except for war time experiance is mind blowing. Looks like arguing this fact for all those years was not in vain.