Water soluble degreasers are emulsifiers that, like soap and detergents allow the dirt/grease mix common on bikes to be
washed off. Organic degreasers (mineral spirits/gasoline/WD40/organic alcohols/diesel fuel/acetone etc) dissolve the
grease to varying degrees and rinse off dirt/grease in that fashion. Alcohols/acetone are to some degree soluble in water
and dissolve grease also to some degree though short chain alcohols are less effective at this than long chain alcohols but
they evaporate faster. WD40 is basically mineral spirits.

Differences in the products mentioned are related to ease and method of application. Liquid/soap types are typically diluted
in water and applied with a brush. Spray on are already diluted and applied with the sprayer which allows use on parts of
the bike like chainwheels where brushes are less useful.

Youtube: https://www.youtube.com/results?sear...lean+your+bike
Would be nice if they started with a dirty bike.