Yes pool chemicals are different sometimes.
But mort of the time they are the same.
Most chemicals purchased in retail outlets have basically the same ingredients inside.
Common chemicals such as: clarifiers, algaecides, pH increasers and decreasers, alkalinity increasers, calcium increasers and chlorine/bromine reducers are basically the same from brand to brand.
Trichlor chlorine tablets are basically the same from brand to brand.
Some brands state 89% available chlorine, others state 90%.
The difference comes into play when a tablet feeder (chlorinator) is used.
Some of the cheaper tablets might gum up the units.
Bromine tablets are basically the same from brand to brand.
Calcium hypochlorite is basically the same from brand to brand.
What is different are enzyme based products.
There are literally thousands of enzymes for different industrial and health needs.
Each enzyme manufactured is different than other manufacturers.
Enzymes do an effective job of eliminating oils, scum, and other common elements pools have to deal with.
Where you might find different chemicals is from companies that make their own chemicals.
For example, there is a difference in some clarifiers.
The most common brand name clarifiers only work on positive and negative ions.
Others work on all types of cloudy pools.
Defoamers is another good example.
Most defoamers are silicone based.
They only work temporarily.
There are some products on the market that have enzymes and clarifiers.
These products actually eliminate the foaming in spas.
Another example would be non-chlorine shock agents.
Some only remove inorganic combined chlorine, some remove organic and inorganic combined chlorine.
Most commercial pools should deal with companies that specialize in commercial pools.
The chemistry needs are different, much more complex.