This is from the Bosche website (which I am surprised you didn't bother to check out):

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Advantages of the Bosch-Battery S3

For older and smaller vehicles
Reliability and Starting Power at the right price
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Advantages of the Bosch-Battery S4

15% higher than standard car-batteries
20% higher service life thanks to innovative PowerFrame technology
For all vehicle classes
Reliably guarantees the energy needed for an average number of electrical consumers (electric windows, radio, air-conditioning)
Meets permanently the high demands made by international car manufacturers in electrical terms (A, Ah)
Also suitable for asian vehicles
Covers 97% of the market

The powerful energy source for safe starting also fulfils the increased convenience demands of middle-class cars. Also, covering 97% of the market helps meet the special requirements of Asian cars.
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Advantages of Bosch-Battery S5

30% higher cold cranking power than standard car batteries
Safe starting also in extreme temperatures
30% higher service life thanks to innovative PowerFrame technology
Fulfills and surpasses original-equipment recommendations
85% Market Coverage
Dependable supply of the safety-relevant extra consumers, e.g., ESP, ABS, etc.
Minimal self-discharge
Extreme short-distance tolerance

Great class calls for great battery power: For powerful engines to start safely and for the dependable power supply of wide-ranging convenience features.
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The power plant for maximum demands: Bosch-Battery S6 with AGM-Technology

The new AGM battery technology by Bosch is absolutely maintenance-free, 100% leak-proof in any position and extremely vibration-proof.

Dependably ensuring the multitude of comfort, safety and system functions of the latest generation of cars requires a battery technology that meets extreme energy demands while promising reliable starting power at the same time. The new Bosch-Battery S6 with AGM Technology (Absorbent Glass Mat) guarantees this power for maximum performance in starting and power supply everyday.

Thanks to AGM-Technology with fixed electrolyte, the Bosch-Battery S6 is extremely cycle-proof and long lasting. Bosch even recommends the Bosch-Battery S6 for middle-class cars with power starting at 3,500 watts and for vehicles with an extreme cycle load, such as taxis.

Constant top performance where others throw in the towel

Starting too many electrical consumers simultaneously will push a generator to its capacity limits. Basic starter batteries can balance this deficiency a maximum of 100 times at the height of their capacities. After that they begin to loose considerable power, which leads to troublesome starts. The Bosch S6 can balance it 300 times. Its high energy flow rate ensures the output and input of lots of energy.

Depending on their equipment, the Bosch S6 is also recommendable for cars currently equipped with a 66 Ah-, 74 Ah-, 88 Ah-, 90 Ah- and a 100 Ah-battery as a standard.

Advantages of the AGM-Technology

Extremely cycle- and vibration-resistant
100 % maintenance-free, tilt-resistant and safe from leaks
Double action time, triple energy flow rate
Installable in any position