Not necessarily so, George...
Many cleaners have the some of the same ingredients, but aren't formulated the same, so if two cleaners have the same active ingredient, they can smell the same, but one can have other ingredients that can be harmful to materials it wasn't formulated to be used on. Many cleaners have added fragrance...and because there are only a limited number of fragrance ingredients that can be successfully combined with ingredients in cleaners (the wrong mix will produce just the opposite of "that fresh clean smell"), it's not uncommon for two entirely different products smell very similar. Most private labelers who do any volume at all don't just relabel another product...the labs who make their products make 'em to their specs. While we were developing bilge cleaners, out lab came up with a citrus based cleaner that was the best degreaser I'd ever seen...it just melted oil and grease that had been stuck to the bilge so long it was the consistency of chewing gum. Unfortunately it also "melted" light plastics and polyethylene. Great stuff for use in a machine shop...but not on a boat--especially not in a bilge where it could come in contact with a plastic water, holding or fuel tank. There are several citrus-based bilge cleaners on the marine market which look smell very much like it, but won't harm anything on a boat. I'm not saying it's a bad idea to look for cheaper household or industrial cleaners, only that there's a big difference between rub rails and white walls--and especially between gelcoat and white walls. Just be very careful with anything that isn't specifically formulated to use on the material you want to clean--and safe to use on anything else it might come in contact with.