I for one separate songs that are classic from those I consider classical vis I can pick songs from many genres as are "classic' of that genre, yet not what I'd deem "classical". Many times a concerto is only a showpiece part of a much larger work. Many of us are familiar with Giuseppe Verdi's Triumphal March from his opera Aida, that is, if we graduated from some academic institutions., Still, I'll deem this song "classic" and that from which it was extricated "classical". For sure, it is a march, but not intended for the performers to be marching in the parade of exodus, their diplomas or certificates of accomplishment in hand. I suppose I could go on and on with such, but I'll not leave this expounding without mention of God Bless America, White Christmas, and thousands of others that I refer to as classic, yet not classical albeit they can also be categorized otherwise. Seems simplest just to say they are what they are in the ear of the beholder. Want to play them with a trumpet, do it. Want to play them with a violin or piano ... do it. Want to walk down the aisle to other than a recognized march ... do it. Play it because you like it ... that's the best! True, it's nicer if you're paid to paid to play it, and sadly that isn't always the reward, with those rare exceptions.