In Star Wars, we see multiple elite Clone Commando variants. These include the ARC Troopers, the commando regiment that Gregor belongs to and the Bad Batch. Canonically, what separates these variants from each other?
Disclaimer: A good chuck of this comes from the Legends books, so it may no longer be canon.
ARC stands for 'Advanced Recon Clone'. Despite their (usual) appearance in the animated series, ARC Troopers were clones specially trained for advanced recon in unfamiliar terrain, and stealth / guerilla operations. They may be comparable to US Army Rangers, in a sense.
Clone Commandos - these were actually nicknamed 'CC's in some novels. Clone commandos are uniquely trained and gifted, drawn from the exceptional clones during training. They are training for commando-type missions, such as sabotage, demolition, and usually work in small teams of Clone Commandos. They are also (on paper) the strongest clones, capable of destroying entire droid armies in just small groups. It should be noted that neither ARCs nor CCs are built from different templates.
'Bad Batch' - these aren't normal clones. Kamino mantains exceptional cloning standards, but they slip up from time to time. Usually it's a clone unwilling to follow commands, but occasionally it results in a clone with a physical defect such as Clone 99 from Clone Wars: Season 3. The Bad Batch is a team composed of clones with defects, however the defects enhanced their specialties (sniping, hacking, brute force, CQC). If you're wondering why Kamino doesn't do that for all the clones, it's because trying to deliberately induce beneficial defects into a cloning process would hit both ends of the spectrums, and the Kaminoans are trying for a uniform army.
Clone Commando is the variant
ARC Troopers are normal Clone Troopers who excelled and received further training as a result. They are CT clones, and part of the genetically identical clone batches that formed the rank and file of the Grand Army of the Republic (also CT clones).
Commandos are genetically diverse, even from each other, as a result of Kaminoan experiments. They are CC clones.