What you're missing is the level of comparison. Everything is different from everything else if you're looking only at differences. But if you want to classify concepts, you need to determine what are the similarities. So, yes, if you're talking about objects in the category of operating systems, W11 and OS/2 are in the same category. If you're looking at languages that offer high level constructs, C and Java are at the same level. Languages that offer only direct machine instructions (assembly) are at an inferior level.