Question about Linux package managers
I have a few questions about Linux and their two most popular package managers: dpkg and rpm. I've been given to understand that dpkg is used by debian, ubuntu, mint, etc... and rpm is used by redhat, fedora, SUSE, etc...
To provide a bit of context: I am developing an exclusively Linux-related petition website to get major software companies to port their programs to Linux (software + games). One of the recurring excuses of certain companies is that "the Linux landscape is scattered", so I figured that maybe if we specify the distro's it should work on within those petitions, the "scattering landscape" won't be an issue anymore. For this chosen distro, I was thinking about Ubuntu because it is the most popular and, at this time, the most ambitious one to break through into mainstream usage (already popular, very user friendly, Steam, nVidia, entering phone market etc.). Also, alot of distro's are based upon Ubuntu's packages, so I figured that programs written for ubuntu should be transferrable to other like Mint and Kubuntu (for instance).
Ok, with that in mind, I can only assume that the theoretical software would be released in .deb packages? If so, would these packages be useful on rpm based distros? A friend of mine said the only difference between them is the way the files are put into a package, but both the .deb and .rpm packages would contain the exact same files for the exact same program. I could not find any info on this, however. I don't want to exclude rpm based distro's, but I also don't want this demand of having both types lower the chances of any port at all. I'm just wondering how interchangeable these two package managers are, and whether it would be a hassle for a company to release both.
Now, if you were me, and you'd have a petition to get Photoshop to Linux for instance, would you specify the package manager filetype you'd want the port in? Or would you let them choose and risk ending up with just .rpm OR a .deb and not both? Or are these so close together that this risk would be neglectable? Keep in mind we're talking about commercial software, so you probably won't be allowed to convert anything yourself...
Looking forward to your insights,