I don't know that I can describe it better than you might be able to see for yourself, say by taking two images of a landscape (where a filter is relevant), as a raw color original, and maybe with a medium yellow filter and an orange filter, and seeing if you can replicate the filtered image by whatever digital methods you have at hand and prefer. It might not be strictly a color conversion effect. Maybe it's the reduction of chromatic aberration that comes with using a strong monochromatic filter, that you may not be getting when you adjust the color channels to produce a B&W image. Maybe it's the result of UV filtration that you might not get without a filter. Anyway, it's worth trying. I don't have any tests saved that I can find easily in my files, but it's not too hard to try it out on your own.