I understand that the difference between "щ" and "ш" is (roughly) the difference between "shya-" and "sha-". But how do you differentiate "щ" and "шь"? For example, I always differentiated, for example "н" and "нь" as "na-" and "nya-". By that logic, to me, "щ" and "шь" sound the same when I pronounce it. Its probably not a very important distinction in practical usage, but I still want to understand why the sounds are different. If anyone can find an audio/video clip illustrating the difference, it would be great!