Here are my thoughts.
For cleaning I use the cheaper generic products, window cleaner, alcohol, etc. Lots of this kinda stuff out there.
For thinning I use the thinner put out by the paint maker. So I have Testors thinner, Vallejo thinner, Createx thinner, etc,
You use a lot less for thinning than you do for cleaning. i.e. Expensive stuff for thinning, cheap stuff for cleaning.
Some argue there is no difference (generic vs brand name) and they may well be right.
I use such small amounts of the brand name stuff for thinner that I'm willing to spend the extra.
My basic reasoning is if the paint job goes really screwy the thinner is one less factor.