Not clinically imp. Budesonide is the most studied and has been on the market the longest. There are many articles written about this subject pertaining to particle size, potency, ...Etc. For practical purposes, the differences are not clinically important. They all do the same thing and are non inferior to each other. If one does not work for you, try the next one.
Not Fair Question. Everybody's genetics are different, so response to steroids between everybody is different. There are charts to show potency on each individual steroid. The most important thing is to find the right medical therapy to get your asthma under control...Not the low dose of inhaled corticosteroid or the type used. Oral steroids are much more dangerous with higher side effects.