The seaweed typically has negligible N, whereas the fish emulsion is a high N fertilizer. so, in my opinion, really not comparable products.
I have heard that orchids really don't absorb from foliar application the way many other plants do. I doubt that it's harmful in any way, but personally I wouldn't make any kind of extra effort to get food on leaves.
Finally: fish emulsion is SO high in N that I make a point of making sure I am also giving sufficient P and K over time. Fish emulsion typically is 5-1-1, that's a very low P and K ratio. I actually don't use fish emulsion on anything but terrestrials and firbark-rooted orchids, as these mediums are the ones which really are known for having bacteria which eat substantial amounts of the N, so they (especially firbark) need high N applications in order for any N to make it up to the orchid.