Ok in short.
In the war the droid armies attack Kamino but it's defenders and the oldest of the new batch of clones defend it successfully.
After that the chief scientist and head of cloning leaves and goes into hiding and is chased across the galaxy by a group of clone commandos, Null Arcs and a couple of Mandos who trained them but thats not important really.
The republic invades Kamino but most of it is destroyed but some of the cloners are captured and taken to another planet, they don't know how to make true clones only the head cloner did and so they're forced to create Spaarti clones which are basically mass produced versions that grow faster but live even shorter lives and are given weeks or month of training rather then years as well as being inferior physically and mentally and so they are far inferior to the original clones.
They're still created from Fetts DNA but without the chief cloner the remainder do not know how to create them perfectly like the chief did and so even with coming from him they're far inferior in every sense.
Get the clone commando series it's all in that and that series is good, sadly the writer ended the series without completing it.
The spoiler below is extracts from the Wikia that explain the Spaarti better then I can.
n comparison to their Spaarti-engineered counterparts. Clones who fully matured in just a year's time received an extremely rushed form of education through flash training.[7] The fastest developed clones—grown in the span of a few weeks—were trained through memory imprints, taken from the original donor and downloaded into the copied subjects. This essentially enabled a clone to learn all of its template's skills, but also carried with them emotional imprints, and thus the risk of mental instability as well.
By the second year of the Clone Wars, Supreme Chancellor Palpatine had established a secondary cloning facility in secret on Coruscant's moon, Centax-2.[20] Under the supervision of Arkanian Clone Masters, the facility was operated by the company Arkanian Microtechnologies and used Spaarti cloning cylinders to produce fully matured clones within a year. Hence, the clones from Kamino were supplemented by billions of clones that were roughly a year old and instructed through flash training.[20][7] But with only a year to grow the clones and prepare them for war, the fighting ability of Spaarti-grown clones was noticeably lower than their counterparts from Kamino. Thus, the overall result of Spaarti technology led to clones with underdeveloped combat and marksmanship skills, including a heavily diminished sense of individuality and self-preservation.
Even before the formation of the Empire, the Kaminoan format for cloning had been virtually supplanted by Spaarti technology. In the final year of the Clone Wars, Palpatine revealed the existence of another clone army that was different from the original in two ways—the new clones were engineered on Coruscant's moon Centax-2 instead of Kamino, and they grew to adulthood in one year instead of ten years.[29] Decades later when Palpatine recorded his legacy into the Telos Holocron, he admitted his preference for the Spaarti cloning process. Though he did admire the achievements made by the Kaminoan cloners, the accelerated growth rate of Kaminoan-engineered clones was too slow in Palpatine's opinion.[30] Even though the Spaarti clones were far less intelligent and combat effective than the clones bred on Kamino, Palpatine was unconcerned with the apparent disadvantages. The Kaminoan clone army had to meet the best standards in order to fulfill their ultimate mission in exterminating the Jedi Order; the Spaarti clones were meant to bolster the Grand Army's depleted ranks so that the Emperor would have an efficient number of soldiers to enforce his reign the first years of the Empire.
At some point during the early phase of the Galactic Civil War, Imperial scientists tried to improve on the Spaarti method by conducting an experiment to create clones that grew into adulthood in under one year. Through the "accelerated cloning process," clones could be engineered to reach maturity in a mere few weeks while their minds were developed through memory flashes based on imprints of a genetic donor's brain patterns. But the procedure was consistently undermined by several flaws that resulted in highly unstable subjects.[31]
Aside from the physical deformities, the accelerated clones were compromised by abnormalities in their brain development. According to the projections of Imperial scientists, all of the accelerated clones were doomed to suffer from mental instability not long after their creation. Some of the clones would remain stable enough to serve as infantry for a year before succumbing to insanity while others would never make it past their basic training. In order to correct the flaws within the accelerated cloning process, many batches of unstable clones had to be created before the system could be perfected.