I don't think this is true: Both are editing programs. The main subject being edited is a single file (as opposed to multi-file projects, like an IDE does). Bot

I don't think this is true: Both are editing programs. The main subject being edited is a single file (as opposed to multi-file projects, like an IDE does). Both therefore need a UI for file handling (load/save their "native" format that exactly represents their internal model), import/export of other formats, undo/redo, etc. For both there is the question how editing multiple files at the same time is being dealt with, i.e. how processes and windows relate to files. Both have to arrange many tools and helpers together with the main view on the file being edited. Both want to have help and documentation. The files being edited support meta-data. Both raster images and vector images are visual and can therefore be exported to other visual representations, and especially both can be printed. So both programs have to deal with printing, page setup etc. The whole topic of colors and color spaces applies to both raster images and vector images. I could go on, but the above should give a hint how much these programs conceptually have in common.