Ok I must have this mystery solved!!!
What is the difference? Which do you prefer? Is one better forsome things then the other???
The difference is night and day. BC is meant to be a main frosting/filling for cake and cupcakes. Also decorations. RI is an egg white based concoction that dries rock hard and is good for piping on cookies, flood work, and decorations on fondant covered cakes. You could never use RI to ice a cake with. Someone else will come along and give some better examples as well!
Way back when, royal icing was made to cover wedding cakes. I have a book called "The Essential Guide to Cake Decorating" and it uses royal icing to cover w-cakes as an alternative to fondant (its from England....maybe they do things differently over there ). It also says to use marzipan as a layer before putting on your fondant (they say sugar paste, same thing).
But _jamie(no makie sheet cakes)_ is right about the others. It can also be used for extension work on cakes (like lace hanging down from the cake).
Oh yes...stringwork! For sure! Something I have not the nerve to try!