Okay, this is going to be a mouthful but bear with me please.
Across all the Spartan programs there have been numerous changes to type and nature of the augmentations.
Let's take a look at each programs augmentation list and then we'll conclude our findings.
1. Spartan 1 (AKA ORION Project)
From Halo Encyclopaedia: "The members of the ORION program were biologically augmented soldiers, using new training methods and the latest breakthroughs in biochemical developments. Augmentations to the ORION soldiers included muscular enhancement injections, pulmonary respiratory enhancements, retina-inversion injections and cochlea enhancement tuning. In addition, mental augmentations were performed to enhance brain functions including enhanced learning capabilities to allow a subject to learn at a faster and higher rate and enhanced motor skills to improve body movements."
Some Orion Project members settled down and had children. "Due to their parents' augmentations, the Spartan 1.1s had to receive injections in order to ensure normal growth without defects." (Miracles Axon) "While born ordinary, it is suspected that they are subjected to numerous augmentations at infancy. Although they were not as advanced as the cybernetically- and surgically-enhanced Spartan-IIs or IIIs, or even their own chemically augmented parents, they were still physically superior to baseline humans." (Miracles.ogg)
On the whole both Spartan 1s and Spartan 1.1s had the same augmentations, the only difference being the potency of said enhancements.
To conclude, the list is:
-Immunity to most illnesses
-Inability to become intoxicated through alcohol
-Decreased amount of time required for sleep
-Increased lung capacity
-Superior muscle density
-Heightened sense of balance
-Accelerated cellular regeneration
2. Spartan 2
The Augmentations issued to the Spartan 2s are assumed to be considerably different than those issued to Spartan 1s. This is because the augmentations now require surgical procedures on top of biochemical enhancement. The enhancements have also a much higher margin of failure due to their invasiveness and potency. As such they require specific gene markers for a viable success as well as been administered at the onset of puberty.
Here is the list:
-Occipital Capillary Reversal
-Carbide Ceramic Ossification
-Catalytic Thyroid Implant
-Muscular Enhancement Injections
-Superconducting Fibrification of Neural Dendrites
3. Spartan 3
Since the Spartan 2 program the technology regarding the augmentations had improved remarkably. They were considered to be a "quantum leap" in terms of improvement. "Most of the Spartan-IIIs' augmentations were chemically induced instead of surgically implanted like many of the Spartan-II enhancements" (Ghost of Onyx). This also allowed the genetic screening to loosened somewhat.
(While never explicitly stated it is assumed these augmentations are just improved versions of the Spartan 2s' augmentations and hence work in the same way and as such confer the same benefits in terms of potency.)
Here is the list:
-"carbide ceramic ossification catalyst" drug
-"fibroid muscular protein complex" drug
-"retina-inversion stabilizer" drug
-"improved colloidal neural disunification solution" drug
"In addition to their chemically-administered primary augmentations, Spartan-IIIs were subjected to a number of surgical alterations to enhance their capabilities. Their circulatory systems were also augmented from the human baseline." (Lessons Learned)
Gamma company also received 3 more drugs:
-Neural-altering non-carcinogenic mutagen
-2 more drugs to counter the effects of the above mentioned drug
4. Spartan 4
The Spartan 4 augmentations are radically different compared to the previous two generations. Due to there being no genetic screening and the subjects being adults, the augmentations were not as effective as previously in order to limit the danger to the Spartan 4s.
"While the SPARTAN-IV augmentations enhance the subjects' strength and speed, the improvements in these areas are not as extensive as in the two preceding programs and their technological underpinnings are considerably different." (Halo Legendary Crate: Data Drop 1)
Here is the list:
-Skeletal engineering series: (Bones are infused with skeletal fullerene lattices, the joints are also reinforced or replaced while the bones are lengthened. The subject's ligaments are reconstructed during the procedures)
-Muscular engineering series: (Muscles are subjected to induced muscular growth and injected with a material that allows them to work harder. Subjects also undergo muscle grafting)
-Neurological series: (The nervous system is "super-myelinated" to increase the production of myelin sheaths)
-Organ implantation: (Aside from the brain, virtually all other organs in the body are either modified in some manner or replaced)
-Circulatory improvement: (The heart is implanted with a synthetic, polythread weave which significantly increases its capacity to pump blood. Chondrocytes are genetically altered to allow for faster clotting. Subject's blood is modified to make the Spartan immune to most toxins. Spartans are also subjected to K5.2 hemoescutcheon, and implanted with circulatory shunts and intelli-fibrin acclimation, likely aiding in the healing of wounds)
-Gene therapy: (lengthening of the telomeres and increasing the effectiveness of chondrocytes)
5. Experimental Phase Spartan 4
"The original plan was to create Spartans with no armor. They'd have unbreakable bones, and be capable of feats of strength normally possible only with armor." (Halo Initiation)
The subjects were described as having the same augmentations as the Spartan 4s as well as a few more. However, these procedures proved to have an unacceptably high casualty rate, killing or crippling nine of the ten initial candidates; the sole survivor, Ilsa Zane, was rendered mentally unstable and began suffering homicidal tendencies.
To highlight some feats: Zane was able to engage a Mjolnir-armored Sarah Palmer in hand-to-hand combat without the use of any protective equipment and survived Palmer violently driving her head into a metal bulkhead face-first, as well as her subsequent prolonged exposure to the vacuum of space.