What's the difference between Weldtite Dirtwash citrus de-greaser spray and the WD40 chain de-greaser? I m planning buying a chain degreaser for my bike,  I gone to two bike shops and they sell different brand of degreaser. 
First bike shop i went to is the shop where I got my ATX fromand He sells wd40 chain degreaser, the second shop i went to they sells some weltite brand lubes and dirtwash cirtus degreaser. 
I m wondering if there is any difference in performance between these two degreaser.
I have used the WD 40 Chain degreaser before and it performed really well, but I havent tried the Dirtwash Citrus degreaser spray and i wanted to see which one worth buying.
Degreasing chains and other metal components is not unique to bikes. There are way to many degreasing products out there to list. On aircraft, we mostly use varsol, but on my bikes, motorbikes included, I have used dish soap and thoroughly dried the chain then oiled it. Lately I've been washing chains in gas mixed 2 cycle motor oil, hehehe, works good.
Dirtwash Citrus degreaser spray is natural environmentally friendly degreaser that is soluble in water, and reasonably easy to rinse off. 
 WD40 chain degreaser is more of a surfactant with petroleum additives. They say it is environmentally friendly, but it contains butoxyethoxy, isopropano, propane, n-butane, and proprietary surfactants.